T21 mystery question

[gb]

Hi everybody,

I finally got my T21 back together after swapping system board and LCD screen.
The only problem remain is sometime it doesn't power up unless I pull out hard drive. Power light blinks and everything go dead. But as soon as I pull out hard drive it power up normally to BIOS. It is not consistant behaviour, which tell me that hard drive is not a problem.
But I guessing it is something to do with ground contact.

Did anybody had a similar problem? Any advice appreciated, because I am getting tired to take this thing apart.

Regards