A1708 820-00840 - Not powering on

[yair37]

no water damage.
20v 0.5a without battery. 20v 2a with battery.
fan spin for 2-3 sec and stop
Main S5, S4 and S0 rails are present.
PPVCCCPU_S0G - 0.9 at the beginning go down to 0v and the fan stop and then go up again to 0.9v and stay stable.
ALL_SYS_PWRGD - 3.3v at the beginning go down to 0v and the fan stop and then go up again to 3.3v and stay stable.
PLT_RST_L -3.3v at the beginning go down to 0v and the fan stop and then go up again to 3.3v and stay stable.

 

[2informaticos]

Did you try the board alone on the desk?
Check for USB activity.

Worth to try known good BIOS...

 

[yair37]

Did you try the board alone on the desk?

yes of course, the same.

there is USB activity.

Worth to try known good BIOS...

HOW?

 

[2informaticos]

USB activity for sure?
Did you see flashing Link LED on USB boot pendrive?

 

[yair37]

yes..i have ssd adapter with blue and red light its work and act like the other....turn on for 3sec then turn of for 2-3sec and then turn on again and stay

 

[2informaticos]

When the board stays on again, Link LED keeps flashing???

 

[yair37]

just stay on...CAPS LOCK light not turn on

 

[2informaticos]

So NO USB activity in fact.
The board turns/stays on, but doesn't boot.

Try known good BIOS.

 

[yair37]

Try known good BIOS.

how i check/try?

 

[2informaticos]

Reflash the SPI chip U6100.
If you don't have Medusa programmer, remove the chip and use classic USB programmer.

 

[yair37]

o.k i have medusa 2 i was read mac rom from good working (same board) and write on this mac(hope this is the right thing)...but act the same

 

[2informaticos]

I hope you've cleaned ME region too.
However board should boot even with dirty ME, if BIOS works in other board.

Probably bad CPU there...