Symptoms:

laptop does not POST (cold boot and hot reboot. wake is fine),

disk LED and monitor backlight(?) flash twice a second,

exaust gets pretty hot.

Attempts:

external power only,

battery power only,

hold power button 30 seconds with no power,

VGA monitor,

left memory stick only,

right memory stick only,

disconnect hard drive,

disconnect optical drive,

disconnect wifi module,

disconnect webcam,

disconnect lcd panel,

replace lcd panel.

Solution:

Hopefully that's where someone jumps in!

What would you point at: motherboard&gpu ... power button ... lcd cable ...