Dell Studio XPS 1647 not booting

I have a XPS 1647 that I bought in this state in brand new condition but with no warranty.

I have been reasonably lucky with resurrecting previous laptops but this one is a little trickier.

When you push the power button you may get either one or three of the media lights comming on and the dvd tries to spin up but after 10 secs stops.

Thinking that it was a bios issue, I have tried disconnecting the CMOS battery, nothing

Tried various Crisis recovery techniques using a USB stick - nothing except the fan comming on high, keyboard lights and fingers crossed.

Any ideas or can / do I send it to Dell ( Australia ) to get a new motherboard if it is terminal.

I reckon I could fix it if I knew what.

Thanks in advance