rfas :
I can't find the jump caps for the firmware reset, but I did try the battery earlier to no avail. I also tried the back switch, no luck.
Are you using an Onboard graphics card?
If you were using a PCI-E card, you should've uninstalled all the files of your GPU first before placing his card onto yours.
If you had a Onboard card(On motherboard)
if you installed your friends GPU, with a CD? Installed files? etc?
Try uninstalling with the CD again, then remove the graphics card and your PC should automatically detect the onboard GPU.
I know this because I just removed my GPU from my pc yesterday for an RMA and I wouldn't get a signal on my Onboard Motherboard till i plugged my GPU back in, inserted CD and UNINSTALLED everything I installed, then I removed my GPU and connected my DVI cable back to my onboard card and voila, got signal.
Also Note, look at the gold connectors on the PCI-E card, make sure non of them have any scratches on them.. if there's a single scratch then that usually causes No Display and booting problems.
and, If your PC still turns on.. there's chances that it isn't actually your MOBO being the culprit, usually when MOBOs get fried, you can't turn on your PC at all. The fact that it is turning on with fans on is still a good sign, you're probably just not getting video signal.
Usually, whenever a PCI-E slot is occupied, it overrides the onboard video, even if you plug in your cables to your onboard Video, it will not work unless you make the PCI-E slot empty. Most motherboards are like that, the PCI-E overpowers the onboard when occupied. So.. Try taking off the card and leaving the slot empty then hook up your onboard. if it doesnt work then use the LAST CARD that actually gave you signal, in this case.. your friend's? and uninstall anything you installed. Then take off the card once again and hook up your onboard.. It should work, if that doesn't work then.. try CMOS Battery reset, which taking off the battery for atleast 15minutes, if that doesn't work then it's most likely your motherboard..