(Redirected) Precision M6500-white screen on boot and black screen on restart

Hi my Precision M6500 has recently started  misbehaving and has the following symptoms.

1.displaying a white screen on power on and a black screen on restart-the OS boots aand one can discern this by the windows jingle  at the end of the boot process.

2. The unit will turn itself on insertion of the battery.

In order to isolate the root cause of these issues I have tried the following without success.

1.replacement memory

2. new display-mother board cable assembly

3.booting with out the SSDS on the system and even at the bios level the symptoms remain.

Has anyone experienced similar symptoms with their unit and if so what was the final fix deployed to resolve these issues.

The system is running an ATI graphics card i have read a little regarding black screens on boot with Nvidia cards ,can anyone confirm whether any of the info out there has any application to the ATI cards.

Thanks

engindigo