A1932 820-01521 20V 0.07A after liquid damage

[it-solve]

I got this 820-01521, which had liquid damage—no major corrosion on the board, some around CC788/9 and CC8A1. I can see slight heat dissipation from the T2 security chip.

PPVIN_G3H_P5VG3S - 12.63V
PPBUS_G3H - 12.62V
PP3V3_G3H - 3.25V
PP5V_G3S - 0V - 0.42Vdc
CHGR_PHASE1 - 12.40V

Where shall I start from?

 

[2informaticos]

Can you see any liquid sign at audio board, flex and connector?
Do you get all AWAKE and SLPS2R voltages?

 

[it-solve]

I am keeping the Audio board disconnected, the board outside of the case.

When the inside case with fan, battery and keyboard connected only - still not turning on

PP3V3_AWAKE - 3.2V
PP1V2_AWAKE - 1.19V
PP1V8_AWAKE - 1.80V

Checking SLPS2R now

 

[2informaticos]

"I am keeping the Audio board disconnected"
I said to check for liquid signs.
Leakage from PPBUS_G3H to any T2 data lines from audio side, could already damaged T2; no matters audio board is connected, or not now.

If mentioned voltages are present, machine should be recognized in DFU mode.
If not, very likely bad T2...

 

[it-solve]

That makes sense.
Yes, there is heavy liquid on the audio connector board. All SLPS2R voltages are present too.
Last shot try in DFU mode then?

 

[2informaticos]

I doubt T2 survived that.
If you cannot complete DFU, T2 is dead for sure.

 

[it-solve]

Seems that's the case. No key/port combination got the DFU mode detected. Shame on Apple for this crappy design.

 

[2informaticos]

Seems they calculated very good this.
Liquid damage puts the machine out of warranty and force people to buy new one.