Compaq motherboard dead!

I have a compaq (1997-98) motherboard inside a Compaq deskpro EP/SB
series 6266. The computer worked absolutely fine except it wasn't able
to recognise a new PIII processor (CMOS setup showed it as PII). So I
downloaded the required BIOS upgrade from Compaq site and ran the
program for a dos prompt. The program ran successfully and returned to
dos prompt.
I then tried to re-boot the machine. It showed absolutely nothing on
the display. Harddisk got initialised and cpu fan went on, but display
showed nothing.. no beeps.
I then thought of clearing the CMOS. Removed all other cards except
display card, also removed HDDs, connected jumper 2-3 (clear)
position. tried with removing the mains, removing battries, also
removing display card, left off for 1/2 hours, left on for 1 hour,
etc. Tried everything but can't get the BIOS to reset or the display
to show anything!
Is my motherboard dead???
Please help me.. any help will be appreciated
Thanks
Nitin