My wife's MacBook was not holding a charge well, then went black and would not power up.
I ordered a magsafe dc-in board and a spudger. They arrived after the expected wait, I followed the instructions and replaced the board. The instructions were easy to follow.
Unhappily, the repair didn't result in a working MacBook. It still won't power up.
Be born rich, and you won't have to fix things yourself.