Chosen Solution
I replaced the battery on my A1989 I’m planning to sell, and now the CPU is incredibly slow, to the point booting takes over 5 minutes, the battery isn’t even recognized, I can’t boot into recovery. How screwed am I, and is there any way to diagnose this?
I would try a PRAM reset and this is how you do it. Turn off your MacBook and then press these keys without turning it on: Option, Command, P, and R. Then, keep holding those keys and press the power button. Nothing should appear on the screen. After 3 seconds, let go of those keys and press the power button. Tell me if this works. Also, make sure you got the genuine Apple battery for it https://www.ebay.com/p/12031120377 If this worked for you, please accept this answer. Thanks!
