820-00165 - Not booting after repair

[Max7]

This one arrived with no green/orange light at all. Physical examination revealed corrosion on C5002.
After replacing C5002, I got USB activity and only with a screen connected booted up fine to the flashing question mark.

I put the board in a case, connected cables and added an SSD; no boot. Green/orange, fan spin, nothing else.
I removed everything one by one hoping to pinpoint the issue but the bare board alone is no longer booting (no USB activity).

SMC bypass does not make any changes.

Don't remember if it is the normal behaviour but upon connecting the power fan spins for about 5-6 seconds, then stops for 1-2 seconds and starts again. It does this just once, not repeated reboots.

Carefully examined the rest of the board for liquid damage however it is very clean with no obvious issues.

Are there any clues above indicating what might be the next problem? I am not sure where to go next.

EDIT:
PPBUS 8.6V
PPVCC_S0_CPU is 1.8V
PPVRTC_G3H 3.3V
PLT_RESET_L 3.3v

Thanks

 

[2informaticos]

This board should start directly, without any restart.

Test the board alone on the desk.
Check all SPI Bus Termination resistors and their traces.
Inspect J6100 for corrosion; clean it, if needed.

You can also try known good BIOS.
Don't forget to make backup first.

 

[Max7]

Well, this morning I recalled that after the board working the first time, I applied liberal amounts of IPA to clean it properly. I suspected that the alcohol went under the SMC as well and perhaps relocated some of the dirt that was already parked there. I Reflown the SMC and now everything is working back again. Lesson learned.

Thanks for the help.