820-00165 corrupted bios Bios?

[jadao]

This one had a drop of liquid near bios and smc. It was booting with some voltages pulsing...

Discovered the Miso pin 2 of bios was not connected because of a burned probe/link point.
As soon as I restored the trace, the logicboard started but while booting to the OS it simply shut off.

I tried an SMC bypass just to see if it's a sensor issue but it wasn't, board was still shuting off in the middle of the progress bar. So I decided to reflow the smc because I saw some greenish crap but it doesn't help at all.

I started to think that at this point it could be anything, then I remember that it was unresponsive to PRAM so I thought maybe the bios got corrupted (that could make sense, no pram + burned Miso probe point) :

And boom this time board doesn't shut down and fully boot to OS with another bios.

So my question at this point is how to tackle this: I take the ME block from my original non working bios and copy it into the working replacement bios and changing the fsys block.

Or I just take a clean ME and copy over the original FSYS block?
Thanks

 

[2informaticos]

Keep original Fsys and ME region.
If works, then leave it as is.

But your symptom usually denotes ME region issue.
Get Medusa which can work on the BIOS chip onboard...

 

[jadao]

I kept original Me and Fsys but it did'nt work, same issue.

So I opened my Medusa package and started playing with it.

It ended up being an ME corruption, I just copied back the original non working Bios to the donnour board testing bios that was already soldered on the board.

I tested it as is in case it was a bad original chip-> same issue
Then I used Medusa to perform a PRAM because it wasn't available ->same issue

Cleaned the ME and worked great!

Conclusion: water drop near bios killed MOSI trace to pin2 of BIOS + Corrupted ME region.

Thanks 2informaticos!