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Macbook Pro - A2251 - No power when battery is connected

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  • manymonsteras
    New Member
    • Nov 2025
    • 1
    • Canada
    #1

    Macbook Pro - A2251 - No power when battery is connected

    I am hoping to get some advice. I have a 2020 13" Macbook Pro - A2251 that wouldn't turn on. I have done lots of electronics repair in the past but never on Macbooks. I have had this laptop sitting around and I finally decided to take a look at it and see if I could spring some life into it.

    First, it wouldn't boot up at all. I did a DFU restore and managed to get it to power on. Did a full restore but the battery was dead and wouldn't charge. I put in a new battery in it but now it won't boot up when the new battery is connected. I ordered a second new battery just in case, but it gave me the same result. If I disconnect the battery management cable, it boots up and let's me into MacOS (albiet very slowly). I don't think I damaged anything on the logic board while I was putting in the new battery, but I guess it's a possibility.

    My USB C multimeter reads 5V and 0.15-0.3A on all 4 ports when the battery is connected. And it powers on normally when the battery is disconnected.

    I would appreciate any advice if someone has some knowledge on this.

    Thank you!
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 15625
      • Canada
      #2
      If the BMS cable is disconnected, the logic board will sense this and throttle the CPU speed and likely force a high fan spin. Confirm the BMS cable is seated ok and is not damaged. If available, test with a known good BMS cable (Amazon?).

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