[mdlug] Laptop Hardware issues

[Raymond McLaughlin]

The laptop: HP Pavilion DV600 series (dv6253cl)
  AMP Turin 64
  NVidia Graphics
  2 GB RAM

The problem: Upon power up a more or less normal POST seems to start,
but the display never lights, and after about 12 seconds it powers off
for about 5 seconds, then starts the cycle over.

A client gave it to me because of this problem.
After I first got it (and after charging the battery) I discovered that
I could "trick" it into booting up by quickly powering it off and back
on again, once it started into this looping behavior. This "trick"
worked several dozen times. Over the course of a week end I got I nice
install of OpenSUSE 11.0 working great, and thought I had a good, if
somewhat quirky, new laptop. Then my "trick" quit working, and it hasn't
booted since.

What I have tried:
  Starting on AC power only, no battery.
  Starting on battery power only, no AC.
  Disconnecting, replacing, swapping all disk drives.
  Swapping in known good RAM (Original RAM passed memtest without problem.)
  Took the whole thing apart looking for loose or faulty connections.
  Tried booting mother board with disk drives, track-pad, and keyboard
disconnected. problem persists
  Reassembled it fail in the same manner as always.

Any suggestions before I start selling off parts?

TIA
Raymond McLaughlin