Uh Oh

Seems I may have fried my brothers mobo. I built this computer for him a little over a month ago. I needed to install a disc drive though so I had the case covers off and went to work. I soon realized I didn't have the right cable for the psu and decided to start the computer back up. Well now it won't start. I have read the it won't start sticky and have tried everything there. The only clue I have is that when I have it plugged in and I switch the PSU switch from O to I after about 1 second the case fans, case light, and cpu fan all start up for a split, and I mean a SPLIT, second. The only thing I can think of is that when I layed the computer down on the carpet the back of the mobo touched the carpet through the hole of the case that is used to install the cpu fan and I fried the mobo with the static electricity of the carpet. Here are my specs,

AsRock z68 Extreme3 gen3
Core i3-2100
Stock cooler
GTX 260
G.SKILL Ripjaws Series 8GB (2 x 4GB)
Corsair HE550 (Old Unit)
Antec Three Hundred Black Steel ATX Mid Tower Computer Case

Any ideas? Could it be my PSU?

You've verified that all the cables on the motherboard are securely attached, including the 24 pin and the 4/8 pin? You need both to start up the system.

Otherwise:
Reset CMOS
Remove all components unnecessary for booting
Remove all RAM and install one stick securely (rotate through the RAM and slots as well)
Unhook everything from the PSU and use some wire to jump the green wire to any black. If it doesn't stay on, it is likely dead. If it does stay on, it is likely a component installed wrong, something shorting, or a bad motherboard.

Thanks for the help. I went to try that paper clip jump start thing and decided to try unplugging every component and checking every connection. Looks like the main mobo connector was loose. Didn't think it would come loose so easily so I didn't think to check it. Everything is powering on now, but no video output. Not sure what to do about that, but at least the computer is starting. I am only assuming it is actually booting up though.

EDIT: Yeah I don't think it is posting it still "starts" even without any RAM installed. Clearing CMOS didn't seem to do anything using the clear cmos button.

Remove the motherboard and sit it in a non-conductive surface. Don't use an anti-static bag. Hook only the basic amount of components to boot (MB, CPU, one stick of RAM). If you can attach a speaker to the board (or if it has a built-in one), it should emit a single short beep once it goes through the POST. If not, start reseating anything that you can reset.

I got it working! It turns out I am an idiot. It was the mobo cable the whole time, but before I figured that out I removed the ram and did not have them properly seated when I re-installed them after I got the cable issue figured out. They took an unusual amount of force to seat, that is why it was not booting though. Thanks a lot for the help though I am sure you get a lot of first time posters like this.

No problem at all. I'm glad that you got it figured out.