Update: I’ve decided I’m giving up on what I have to work with, and I’m gonna buy a new battery.

I have a 13 inch MacBook Pro that I have been working on refurbishing, and I’ve run into an issue where if I unplug it from the charger it shuts down and it won’t show battery percentage. I think this might have something to do with when I was dusting out the insides of the computer and a misaligned flex cable, but I am really not sure. Here’s an image of white happens when I first turn on the computer: enter image description here

i’m really at a loss as to what to do at this point, because I’ve just been scouring forums for the better part of a month.

  • What does the Power section of System Information say?
    – Barmar
    Aug 6, 2021 at 13:52
  • What year of MBP?
    – benwiggy
    Jul 27, 2022 at 21:29

2 Answers 2


Either the battery is not connected or it has failed.

Did you receive any messages about “service battery”?

You will likely be taking the cover off again to check.

  • I don’t believe I’d received any such message, though the battery not working would make a lot of sense. I’ll have to test that theory tonight
    – Kai
    Aug 6, 2021 at 11:32
  • It might be interesting to run the Console app for a while and see what messages are appearing there Aug 6, 2021 at 15:21

I have just replaced a battery in a 2016 MacBook Pro 13 with a third party replacement. It was the last part of a fairly major exercise to replace the keyboard. When I turned the laptop on it worked while plugged in but failed as soon as I removed the power cable. Turns out I had failed to transfer a cable from the old battery I had removed to the new replacement. Once I had put the cable in it started working although I am seeing some concerning entries in dmesg which I suspect is related to the third party battery not having the same hardware as the genuine part (update: actually was due to a faulty third party battery):

Failed to read nominal voltage rating key . voltage:0 rc:0x84

The cable is the one in the picture below from ifixit battery replacement guide. I would check that it is connected correctly at both ends - something you will need to do regardless even if you are only replacing the battery.

enter image description here

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