820-01521-A with liquid damage but no corrosion starts with 5V then turns and stuck at 12V

Hello my customer brought me a macbook 820-01521-A he said he poured water on it but when we took out the main board didnt find any corrosion depends on a water damage. When we plug the DC cable with all connectors unplugged main board starts with 5V 0.200A then turns to 12.15V 0.00A and this jumps always between 0.000A and 0.100A.

I have read all articles about this main board and checked J6100 rails to T2 chip on diode mode and found out no short but when I check the board under thermal camera while its starting i can see T2 chip flashes out but the temperature stays around 40C degrees

I dont know where to start, could you please show me a way for this?
we have found out that R0211 and C0255 has been corrupted by corrosion. So do you think changing these will sort out the problem?
but no short on diode mode. It shows 715 on diode mode
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I have just found out that when I plug in the battery connector which is J6950 then starting voltage stucks at 5V but without battery connector plugged in it starts with 5V then jumps to 12V and stays there
R0211 and C0255 is on audio board not on the mainboard.I have changed the U7000 but now I found out that under the thermal camera U7800 flashes on some point and I guess it belongs to PP3V3_G3H line where it flashes. When it flashes it went down to 0 and back to 0.1A again. It starts with 5V then goes up to 12V but on 12V stays but it jumps down to 0.00 from 0.100A I ralised that on PP3V3_G3H line it goes up to 3.3V but then jumps down to 0-1V then back to 3.3 again. And it loops like this. Nothing connected to the mainboard.
Any suggestions?


Staff member
Liquid spill on audio board, usually damage T2 on this board.
You should compare diode mode readings on J6100 with known good board.
At least check if any short there...
so if it is t2? what should I follow? changing t2 with a new one will sort problem out? Or do I need to do anything if I change t2?


Staff member
Changing T2 will lose fingerprint functionality.
Several times I found T2 damaged on SPKRAMP_RESET_L line (internal short).
This line is next to PPBUS_G3H on J6100 and audio board connector too.