Blank screen after installing new motherboard

Well Lads,

Hope you can help.

Have a Toshiba laptop. (Don't have the spec with me at the moment but its silver and about 9 months old - pretty good spec)

About two weeks ago I tried to turn it on and nothing. Just a power light and nothing else. Turns out that I shorted it out with a damaged USB port and thus voided the warranty.

I bought a new motherboard and installed it last night.

Now the power light is on, the fans starts and stops and I can hear the hard drive clicking away but a blank screen. All mounted and connected up fine from what i can see. Tried booting with everything on a piece of cardboard to make sure it wasn't the casing and the same result. No fail sounds coming off the motherboard. Ram mounted correctly. Tried switching out the Ram and booting with each of the respective RAM boards.

I'm thinking either:
- RAM got damaged when i shorted the motherboard
- Processor is damaged
- Motherboard is DOA

If I'm missing something obvious I'd be delighted to try it. If you need any other info just shout.

Fingers crossed