This is important. Battery not charging is a common fault. Sometimes it is a bad battery. Most of the time liquid damage has done its damage. The SMC must see proper battery present, battery charge control IC is a middle-man in this communication channel. If I find these signals at the battery – it proves all.
Check battery charge data line;
I like Pomona test leads, There is no such thing as a good CHEAP bench meter. It’s my livelihood – this Keithley 2001 is a good one for me. Doesn’t fall into battery saver auto-off in the middle of chasing down a problem…got enough on my mind at such a time…
Ahhh – the TPS51125 IC chip. It should give your macbook board the 3.3V and 5V it needs. The 3.3V is *so* important…This is what we need for the power button to work.