Dead CPU, MB, both or neither?

[Bombhead]

Looking for some genius here to help me out, would really appreciate it.
I have a dead laptop.

Asus X5EA
Switch on: (with battery)
Power light on.
Batt charge light on.
DVD player makes a brief "zzz" noise.
No fans.
Hard drive makes normal sound but no activity light.
No video at all.
No attempt at post.
Power light on

Switch off: Have to pull DC power supply and remove battery to stop activity.

Switch on: (without battery)
Power light on.
DVD player makes a brief "zzz" noise.
No fans.
Hard drive makes normal sound but no activity light.
No video at all.
No attempt at post.
Power light on

Switch off: Have to pull DC power supply to stop activity.

Have stripped it down and rebuilt it twice, looking for a loose connection, everything fine.
Have cleaned off/replaced thermal paste on CPU and graphics chip and cleared dust from every nook and cranny.
Have changed cmos battery.
Have removed battery and held power button for 30 secs.

I had a feeling it was stuck on hibernate, but I've put the hard drive from the broken one into another laptop and it boots fine.

At my wits end.

I reckon it's either the CPU or the motherboard. Or both. Or neither. Aaaargh!

 

[sourodip]

Do you see the MB's LED light getting turned on?if not,then it's the cpu otherwise it's the MB?does the psu's fans get started?