820-00840 X in battery icon [LIQUID DAMAGE]

[Soro]

Hello,

I have an A1708 with an 820-00840 logic board.

This came in with liquid damage and initially, it did not start at all.

I cleaned the corrosion best I could with the trusty toothbrush and alcohol and now it starts but the battery icon has an X in it.

The closest video I could find on this subject was this “Macbook logic board repairing X in battery after liquid damage 820-2936”


I’ve followed the steps accounting for the slight differences in the boards.

While Louis got nearly 0 when measuring R5380 and R5381 in diode mode, I’m getting about 0.410 dropping down to 0.360 for both.

I don’t really know how to proceed now…

Thanks for your help!

 

[2informaticos]

Do you get 3V at both SCL/SDA lines of battery bus?
If SMC is OK, you can see some pulses there with o-scope.
Even DC voltage pulses sometime 3.1-3.4V, but that is not always visible.

However if liquid went to battery, you must try another.
You can waste lot of time, only for a bad battery...

 

[Soro]

I get 3.4V for both SCL and SDA lines on the battery bus.

I don't have an o-scope.

I'm new at this but from what I've gathered it's pointing to a bad battery... is this a "correct" assumption?

I don't have a known good battery in stock but I'll order one and try it out

Thanks

 

[2informaticos]

Always better to try new battery in case like this.
You can just waste the time on the working board.
But if you get a "ghost" chinese battery, you can waste more time even.

 

[Soro]

Tried out a new battery and still the MacBook only powers on when plugged in and there's an "x" in the battery icon.

I'm been having trouble getting the battery data cable plugged in on the batteries daughter board side so when I tested the original battery and the new battery it was without the battery data cable plugged in.

Could this be causing the "x" I'm seeing?

EDIT: Figured out the answer. Yes, the battery data cable is CRITICAL.