Hi all,
I spent almost 3 days on my pavilion PC trying to recover it after a Win 10 migration.
After having removed all the connections as well as cleared the CMOS battery nothing improved. I knew my PC was not dead because removing the DDR3 it started with the buzzer noise.
The root cause is the Windows fast boot in a corrupted environment (non working Win 10) and the fact my external keyboard was slower to boot-up than the PC itself.
The corrective action was to push the Reset (jumper or short circuit on OT-RST on mother board) so that keyboard was up and running when the main board starts. They hitting F10 or DEL was taken into account and I could modify the boot options to get rid of the corrupted WIN10 install.
Hope it will help you before you thru away your MOB.
Cheers
TMART