Overheated PC caused video to stop working.

HP Pavilion Media Center A1640n (Core 2 Duo 1.86 GHz, 2 GB RAM, 250 GB HDD) upgraded to 4g of ram also have an Asus ati 1950xpro video card.

My computer overheated a few days ago. I was attempting to play a game (WoW) and the screen when black and shut down. So I did standard cleaning; removed my heat sink and use a air compressor to clean it, cleaned the processor and use new cooling paste. Removed the video card and cleaned it up a bit. put everything back in its place and now I am not able to get a video feed at all.
I have since removed everything from the case and then put everything back in, assuring that I have reconnected everything the correct way - still nothing.
I put in a different video card and nothing. attempted to use the integrated video card and nothing. (though I think I disabled the integrated card when I installed the Asus video card)
I have tried several different monitors and cables; 2 of which I know for a fact is working.
Something else I have noticed on the asus card. when its installed and I turn the computer on there is a little red light on it. I have not noticed it before but there is a chance that I just never looked. not sure.

The only thing I can think of is somehow when I removed the processor I damaged it. Though I don’t think that would cause the video out to stop 100%.
Or that the mobo was damaged and caused the video to stop working.

Anyone have any ideas how to fix it? Or an explanation of why its broken beyond repair. Thanks for your time!