I own an alienware m17x laptop that has 2 8800m gt graphics cards that are in sli. Somehow water got spilled on the laptop and it was turned on. The water only got on one of the graphics cards and it had some burn marks and such on it. I replaced that graphics card with the exact same graphics card but when i turn the laptop on i still dont get any response from the monitor.
Have you tried to use an external monitor on the laptop to see if you can get anything on it? It's possible that you've disconnected a connector somewhere along the way, which would be the best case scenario for you, and to check that the easiest thing is to use another monitor.
The only thing I can think of is that somewhere you've disconnected a connector and it wasn't plunged back in properly. Open up the laptop and make sure all the components you can get to are plugged in securely.
I called alienware and they said that the master and slave graphics cards have a different bios installed on them. The graphics card that got the water damage was the master card and i ordered one that was a slave card in a different laptop. So i am returning the one i ordered and going to try a different one.