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Alienware 15 R2 CMOS Battery Replacement

Introduction

This guide will show you how to replace the CMOS battery in an Alienware 15 R2, a critical component in the laptop that powers the BIOS chip and updates certain system settings like date and time while the device is shut off. When the CMOS battery stops working, it can cause symptoms such as incorrect time and date, BIOS errors, or even issues booting the device. Before you go through this guide, make sure to unplug your computer before working with the inner components to avoid releasing an electrical charge into sensitive technology. Failing to do so could permanently damage your computer.

What you need

  1. Alienware 15 R2 CMOS Battery Replacement, CMOS Battery: step 1, image 1 of 3 Alienware 15 R2 CMOS Battery Replacement, CMOS Battery: step 1, image 2 of 3 Alienware 15 R2 CMOS Battery Replacement, CMOS Battery: step 1, image 3 of 3

    • Place the laptop upside down and remove the two 9 mm screws with a Phillips #0 screwdriver on the top right and top left of the back panel.

    • Remove the four 18 mm screws with a Phillips #0 screwdriver.

    • Remove the four 10 mm screws with a Phillips #0 screwdriver.

    • Remove the back cover by using the iFixit opening tool to separate it from the back of the laptop and pulling it off.

    Edit

  2. Alienware 15 R2 CMOS Battery Replacement: step 2, image 1 of 2 Alienware 15 R2 CMOS Battery Replacement: step 2, image 2 of 2

    • Two clips secure each RAM module in place, one on each side. Using your fingers, spread the clips away from the RAM module.

    • Repeat for the second RAM module.

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  3. Alienware 15 R2 CMOS Battery Replacement: step 3, image 1 of 2 Alienware 15 R2 CMOS Battery Replacement: step 3, image 2 of 2

    • Use a Phillips #0 screwdriver to remove the 3 mm screw from where the RAM modules used to be.

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  4. Alienware 15 R2 CMOS Battery Replacement: step 4, image 1 of 1

    • Use a Phillips #0 screwdriver to remove the six 6 mm screws from the back casing.

    • You can stick your finger in the hole next to the SSD slot for more space to separate the back casing from the keyboard.

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  6. Alienware 15 R2 CMOS Battery Replacement: step 5, image 1 of 1

    • Lift the keyboard off of the frame of the laptop.

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  7. Alienware 15 R2 CMOS Battery Replacement: step 6, image 1 of 1

    • Using your fingers, disconnect the TRON light cable from the motherboard.

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  8. Alienware 15 R2 CMOS Battery Replacement: step 7, image 1 of 1

    • Using a Phillips #0 screwdriver, remove the three 6 mm screws securing the battery.

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  9. Alienware 15 R2 CMOS Battery Replacement: step 8, image 1 of 1

    • Using your fingers, lift the battery out of the laptop's body.

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  10. Alienware 15 R2 CMOS Battery Replacement: step 9, image 1 of 1

    • Use a Phillips #0 to remove screws from the motherboard.

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  11. Alienware 15 R2 CMOS Battery Replacement: step 10, image 1 of 1

    • Using your fingers, pull out the motherboard.

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  12. Alienware 15 R2 CMOS Battery Replacement: step 11, image 1 of 1

    • Disconnect and remove CMOS battery.

    Edit
Conclusion

To reassemble your device, follow the above steps in reverse order.
Take your e-waste to an R2 or e-Stewards certified recycler.
Repair didn’t go as planned? Try some basic troubleshooting or ask our Answers community for help.

One other person completed this guide.

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jesse

Member since: 09/08/25

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University of North Texas, Team 3-2, Coppersmith Fall 2025 Member of University of North Texas, Team 3-2, Coppersmith Fall 2025

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