I have recently gotten my hands on a Mid 2015 15” MBP that was running slow, hoping I could get it fixed back up for personal use.

The previous owner had apparently swapped the old battery out with a new iFixit replacement one and then immediately sold the device as it has been running slow ever since. Using IntelPowerGadget on OSX or Task-Manager on Windows shows the CPU constantly being clocked down to 0.8ghz. This is definitely not thermal throttling as the chipset never exceeds 50C, there are also no faulty sensors when checking with HWMonitor.

The original battery had been discarded so I cannot check whether this issue is actually caused by the battery at all, however inspecting the battery visually and using CoconutBattery I can see that it is not an OEM battery since there is no battery serial number being displayed. Running the hardware diagnosis (holding the “D” key at startup) reveals that the battery might have problems but it says I should still be able to use the device without any noticable changes, showing the error code PPT004.

I then went ahead and bought this used original A1398 battery, thinking it was salvaged from another Macbook, however it ended up being some sort of refurbished third party battery causing the same issues again so I will have to return it anyway. The values shown on CoconutBattery are similar for both batteries (both less than 10 charge cycles, etc.) so I have just attached an image of the iFixit one below.

The machine itself is in mint condition, I have made sure to look for any water damage on the logic board but it seems perfectly clean, after all the device can be used flawlessly with the exception of it running at 1/4 the supposed speed.

I did come across similar threads however they were usually regarding older macbooks or were only having this issue intermittently when plugging in an external monitor, etc.

Others proposed just deleting the IOPlatformFamily.kext from OSX to get rid of the Intel Speedstepping feature, however this method is somewhat outdated and seems like a stupid idea anyway. A similar solution was being shared here, however that is again just circumventing the issue instead of fixing it, and even then Im not sure that would at all.

Essentially I just want to know two things:

1. Is this throttling behaviour really linked to a 3rd party battery instead of a logic board fault, and if so, why would anyone buy or manufacture such batteries if they make the device useless? If this is the case there should have been plenty of others with this exact issue, yet I have only found a few threads discussing a similar issue
2. With the iFixit as well as the other “genuine” battery not working as intended, where would I even begin looking for an actual OEM battery within Europe without having to get it replaced at an Apple store?

I never had any issues replacing the battery on a 2012 MBP, so Its fair to say this behaviour could just be another one of Apples shenanigans to get peoples devices fixed at Apple only and nowhere else, but I just couldnt find a definitive answer especially since I dont have the original battery to compare against.

I wouldn’t know where to ask otherwise, so any reply would be very appreciated!

Update:

I have tried using ThrottleStop on BootCamp Windows according to this thread, this does however also not work. Deleting the IOPlatformPluginFamily.kext as mentioned in the same thread is not an option since it does not even exist on my OS X Catalina installation.

Final Update (Found a solution):

So it turned out not to be a battery related issue . The person I bought the device from stated the issue appeared after swapping it for an iFixit replacement battery, but after buying yet another OEM battery the problem still persisted.

Instead, the issue was related to the CPU current sensing circuitry. I didnt manage to find accurate boardview and schematics for my specific model (820-00138) so I had to use this XinZhiZao (similar to ZXW tool) maintenance program which had the correct board layout to find the problem.

The issue was caused by the "SMC_CPU_IMON_ISENSE" line which is produced by the U7200 power management IC. This chip is responsible for measuring the CPU power usage among other things, and sends the signal through R5530 directly to the SMC. This line was permanently stuck at 1.8V which made the SMC read a high CPU power draw, so it throttled the CPU to 0.8ghz clock for safety reasons.

I ended up running a jumper (blue) from this line to ground, thus forcing the line to 0V.

This way the system now reads CPU current as 0W and I can finally use the machine with its intended performance. No lags, everything finally runs smoothly. It also no longer gets stuck in sleep mode after closing the lid.

Obviously this fix is only a workaround as I still dont know what was pulling the line to 1.8V, so I assume it was either the SMC or U7200 which shorted the line to a neighboring power line somewhere. I didnt want to risk ruining the SMC by reballing it so shorting the pad for C5530 to ground seemed easier to do. However this means there is a constant 1.8V short to ground so I might want to replace the jumper wire with a resistor to avoid losing much battery power being wasted into the short in the future.

In conclusion, the built-in Apple Diagnostics (Holding down Cmd + D on startup) did find an issue, however it was not related to the battery but rather the SMC or U7200. My assumption of having to use a OEM battery was wrong, as it also now works just fine with the replacement iFixit battery. I used HWmonitor on OSX to check the “CPU Package Total” readings, which were at 100 watts and above. After the fix it is reading -W, so the remaining battery time estimations might be inaccurate, but it technicallly isnt necessary.

Im not exactly sure how a simple battery swap could have caused this issue, but since I didnt find much information regarding Macbooks being throttled to 800mhz CPU performance, make sure to check all temperature and current readings using some sort of monitoring tool like mentioned above. A faulty temperature sensor might possibly cause a similar issue.

Hope this helps

⟐ Answered August 25, 2026 at 17:05 MST

The issue:

1. With the new battery, the MagSafe light stays green. System Information sees the battery at 33% (2308mAh) but shows 0 Amperage and "Not Charging."

2. If I unplug the MagSafe, the laptop immediately shuts off.

3. I reinstalled the old (bulging) battery to test. It shows 100% (4322mAh) and "Fully Charged," but the laptop still shuts off immediately if the power cord is disconnected.

4. CRITICAL FINDING: The battery indicator button (on the left side) ONLY works when the MagSafe is plugged in. When plugged in, it shows 3 LEDs (consistent with 33%). When unplugged, the indicator button does nothing.

5. I have already:

- Reset the SMC and NVRAM/PRAM multiple times.

- Verified I am using an 85W MagSafe adapter.

- Reseated the battery connector and inspected the logic board pins.

- Ran Disk Utility First Aid.

Is it possible the original bulging battery blew a current-sensing resistor or a MOSFET on the logic board? What specific components should I test with a multimeter to diagnose why the battery rail is not being energized?

Here is an image (maybe) of the coconut app and the system report.

Here is an image of the system report with the bad battery

=== ===

⟐ Commented August 21, 2026 at 11:54 MST

This is my progress on removing the anti-glare coating after 2 hours. I tried Listerine, 90% alcohol, Peek Metal Polish, anti-bacterial wipes, bleach, and nail polish remover w/ acetone (before I read that someone else damaged the glass itself because of acetone). Luckily, my glass is still fine. Unfortunately, I haven't made much progress as you can see from the picture. I'm confused to why none of the solutions isn't working for me. Some said that Listerine alone worked well along with a microfiber cloth. I tried that but since it didn't work I moved on to try all the other solutions I mentioned. Is anyone else having this issue dispite of trying all kinds of solutions? And is there any other alternatives that would make it simple to remove w/o much time being spent?

⟐ Commented August 20, 2026 at 13:25 MST

Before replacing the old logic board, I erased the machine and attempted installing macOS on it to make sure my time machine backup worked correctly. But as I was reinstalling, the MDM for my company showed up. This brought up a some questions:

1. Is MDM tied to the logic board or will replacing it still lock me out?
2. Has MDM been enabled on my laptop the entire time I've used it and I just didn't know? I haven't heard from the company so do they just not care?
3. Will MDM be linked to my Time machine backup? If I restore from my time machine backup on the new logic board, will my old company be able to track it? Is a fresh install a better idea?
4. Is it possible to bypass MDM so I can reuse the old logic board?

I've tried booting off a flash drive to avoid connecting the the MDM servers in hopes of bypassing the need for an internet connection, but I get an error saying a critical update is needed in order for me to complete the install

I am also unable to restore my time machine backup for some reason. Any reason MDM would cause issues? I loaded the time machine backup but it keeps getting stuck at page with the Apple logo with the loading bar. All troubleshooting leads back to a fresh install which I can't get past because of MDM. Hopefully there is a workaround.

Would appreciate any insight/advice.

Thanks!

⟐ Commented August 14, 2026 at 18:33 MST

I’m looking for some advice on a 15-inch MacBook Pro 2017 (A1707).

The MacBook suddenly stopped working and now shows absolutely no signs of life. I stripped it down and removed the logic board for inspection. I found what appears to be a burnt component(photos attached).

The marking on the damaged component appears to be:

C21 36 N7 G

Can this component be replaced on its own, or is it more likely that something else has caused it to fail?

Is it worth sending to a repair specialist / can I do it myself or is it dead.

There has been no known liquid damage, and the rest of the board looks visually clean.

I’d really like to save the laptop if it’s economically repairable, and ideally preserve the data that’s stored on the soldered SSD.

Any advice or experience would be greatly appreciated. Thanks!

⟐ Commented August 02, 2026 at 14:07 MST

I have a black screen on a macbook pro retina late 2013.

I already tried all the software fix like resetting NVRAM and SMC.

i’m trying to find a way to be sure it’s a harware failure from the screen.

The computer works fine since it’s booting and i can link it to a tv to see the desktop, so it’s not the graphic card either.

The computer got water spilled from the ceiling on the left side of the screen and it got all the way inside through the keyboard. The water quantity was very small, still the mac gave out instantly. Now it’s rebooting fine but without the screen.

I would like to find if the screen is done for good or if the connexion to the logic board is screwed. After opening the mac nothing seems to point that the logic board or the display cables have suffered.

I have a working screen from a mid-2012 macbook pro i could install for testing but i dont know if it’s compatible. On the Ifixit shop the two screens have 50 dollard of price difference, although it has the same spec, also i dont want to mess with my working macbook.

I know i could launch the apple diagnosis but it seems i cant make it display on another screen via HDMI.

Any ideas to rules out possibilities ?

Thanks for reading.

⟐ Answer edited July 29, 2026 at 5:34 MST

So if anyone can help a new diy repair guy out it would be much appreciated!

⟐ Commented July 29, 2026 at 2:49 MST

I’m looking for a board-level diagnosis for my MacBook Pro Retina 15” Mid 2015 (A1398).

Configuration

• Intel Core i7
• 16 GB RAM
• macOS Monterey 12.7.6

History

Before repair:

• The original internal display was cracked but still displayed an image.
• The Mac worked perfectly with an external HDMI monitor.

During repair:

• A technician installed a display from a MacBook Pro 2013.
• The replacement display never worked.
• He reinstalled my original cracked display.
• Since then, the internal display has been completely black.

Current behavior

If the internal display cable is disconnected:

• Apple logo appears on the external HDMI monitor.
• Startup Manager (Option key) works.
• Internet Recovery works.
• But when booting from Macintosh HD, Recovery, EFI Boot or a bootable USB, the Apple logo appears, then the screen goes completely black.

If the internal display cable is connected:

• The internal display remains completely black.

The Mac appears to continue running:

• keyboard backlight works,
• volume keys work,
• fans operate normally,
• but there is no video output.

Already tried

• NVRAM reset
• SMC reset
• Safe Mode
• Internet Recovery
• Bootable USB installer
• OpenCore Legacy Patcher

Always the same result:
Apple logo → black screen.

Verbose mode also showed messages including:

• device is not readable
• failed to initialize volume keybag

Questions

1. Could installing a 2013 Retina display on a 2015 A1398 have damaged the LCD connector or another logic board component?
2. Which is the most likely cause?
   • LCD connector
   • LCD power/backlight circuit
   • Display cable
   • GPU
   • SSD/APFS
   • Logic board
3. What measurements or board-level tests would you perform before replacing parts?

Any advice would be greatly appreciated. Thank you.

⟐ Commented July 23, 2026 at 13:03 MST

⟐ Answered July 21, 2026 at 18:32 MST

⟐ Commented July 19, 2026 at 12:47 MST

Hello everyone,

Hope you all had a good week.

Just a quick one, do we think this is safe RE: Attached image. I asked AI but I wanted a fellow tech heads opinion. I'm also in a tight spot right now so cant exactly change it straight away.

Thank you in advance.

⟐ Answered July 17, 2026 at 19:56 MST

Original symptoms were short battery life and touchpad physical clicking not working. I bought a replacement battery and touchpad.

Battery was definitely bulging and putting pressure on the touchpad. I swapped out both and when booted back up - no mouse movement or clicking at all from the touchpad. External mouse works fine, so I went into system preferences and then Touchpad. It said "Touchpad not detected" or something along those lines and had a spinning circle indicating that it was searching for bluetooth touchpads.

So I opened it back up and swapped in the original touchpad - mouse movement but no clicking. But still, system preferences says it doesn't detect a touchpad (I was hoping to at least turn on tap to click.)

So, what am I missing? Is there some extra step to set up the touchpad with the OS? Does the lack of movement on the replacement pad mean that it's DOA?

Thanks for any help!

⟐ Answer accepted July 11, 2026 at 16:28 MST

⟐ Commented July 07, 2026 at 2:40 MST

This is how it looks

⟐ Commented July 06, 2026 at 13:05 MST

video of issue

Screen

Display cables

Or logic board issues

⟐ Commented July 06, 2026 at 9:02 MST

⟐ Answered July 04, 2026 at 17:11 MST

⟐ Commented July 04, 2026 at 2:46 MST

I replaced the battery in my Late 2013 Retina MacBook Pro 15” (A1398, logic board 820-3662-A) using the iFixit guide, which required removing the logic board.

While removing the heat sink, three of the four threaded mounting bosses separated from the logic board and remained attached to the heat sink. The heat sink screws were extremely tight, but I did not use excessive force or power tools.

Photos are attached showing:

• the detached mounting bosses still attached to the heat sink,

• the corresponding locations on the logic board,

• and the overall board.

The board itself does not appear to have torn fiberglass or obvious PCB damage.

The Mac now powers on and reaches the macOS login screen, but after several seconds the fans ramp up steadily and the machine shuts off. Before concluding that this is a thermal issue, I’d like to understand the mechanical failure.

My questions are:

1. On the 820-3662-A board, how are these heat sink mounting bosses originally attached?

2. Is this a known failure mode, or does it suggest the machine was previously repaired?

3. Can the bosses be properly reattached, and if so, what is the correct repair method?

4. If they cannot be repaired reliably, what is the recommended solution?

I’d appreciate hearing from anyone with board-level repair experience on this specific model.

⟐ Answered July 02, 2026 at 6:25 MST

Mac was inside of suitcase and it was inside of a bag.

Mac boots up,I can hear the chime,but the screen is totally black,not even “light” black. Caps lock light doesn’t work.

I tried SMC,PRAM reset, didn’t work.

Reconnecting screen display by unplugging those two things didn’t work. I used this video

Reconnecting battery didn’t work.

I also tried SMC,PRAM reset while the battery was disconnected and Mac was getting energy from the charger. Didn’t work. I used that video.

What else can I do before changing the screen?I don’t want to swap screen cause it’s expensive.

⟐ Commented July 01, 2026 at 22:25 MST

I’m looking for recommendations for good Apple repair shops experienced in microsoldering on Mac Book Pro logic boards.

⟐ Commented June 29, 2026 at 5:05 MST