820-00928 - no boot

[Mineccia15]

Hello everybody

I'm trying to fix an 820-00928 board.
Maybe this is the weird board ever and in my opinion will be a no fix, but I would like to have an opinion from experts.

The CPU and GPU gets hot, and machines takes up to 20V - 0.89.
All the important signal are there at the same time.
No strange area gets hot, and no trace of water damage there.

Fans are spinning, the keyboard uppercase led never gets on and always no image.

What should I check? Or I can just give it back with no fix?

 

[2informaticos]

What said the client about the problem, when appeared?

Check CPU core voltage (L7211) after 10-15 seconds; should drop to 0.6V aprox, when board boots.
PLT_RESET_L comes high?
You can try full known BIOS.

 

[Mineccia15]

CPU core voltage (L7211) is present ~0.7V
PLT_RESET_L is present 3.3V

working on it I notice that the machine randomly goes back to 19V - 0.2A and than up to 19V - 0.75A. it only happens 1/2 times when I give power to the board. I will try BIOS.

 

[2informaticos]

CPU core starts with 0.7V, or it drops from initial 1-1.1V?
If yes, check for USB activity.