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Model A1990 / EMC 3359. Released in May 2019 with new 6-core and 8-core processor options.

MacBook bms not working. Please help

So when my bms daughter board cable is plugged in it won't turn on. After installing new ifixit battery and bms cable. It won't turn on with the bms cable. Could it be the security settings? It happend before

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If your MacBook won’t power on when the BMS cable is connected, it’s likely a hardware issue rather than security settings, most often a bad BMS board, faulty cable, or improper connection after the iFixit battery install. Try reseating the cable carefully, inspect for pin damage, and test with the BMS if possible to isolate the fault. If it still refuses to boot, the logic board may be rejecting the BMS signal or there’s a short somewhere, so you might need a professional repair cause it can get tricky fast.

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3 Comments:

It happens with both cables

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I have 2 bms daugherbiard cables

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@joel39944

If both cables fail its probly not them, check the BMS board and logic board connector for tiny damage or shorts and try a full reconnect cause something there isnt talking right.

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Are you sure you have latched the cable?

Both the logic board and battery have ZIF connectors which people have a hard time with. There is a compression latch which needs to be lifted before removing the cable and held open when you then insert the ribbon cable, once the cable is correctly inserted the latch then needs to be set to hold the cable firmly against the contacts.

It's not uncommon for the latch to go flying as it doesn't take that much pressure to lift it so while you put the cable in there is no compression! Here is the latch being lifted from the down position to the raised. Is your latch missing?

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3 Comments:

It is latched. Heck itemtified in windows. Unplugging the laptop from wall? Dead

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Also windows says it's at 52%

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@joel39944 - Sadly the logic board needs repairs.

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Joe L will be eternally grateful.
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