shorted motherboard?

so my brother was building a pc after he got all the parts. He put everything together and powered it up but there would be no signal on the moniter. Not only that but there would be no signal on the keyboard when it was plugged into the usb. We plugged in the mouse and it flashed the red sensor light for a second and turn off, if it's put in halfway then the light would stay on. We took it apart like three times making sure everything was tightened and placed right even trying it out outside of the case and still the same results, and no beeps from the motherboard.
Prior to that problem, my brother didn't put in the spacers when he screwed on the motherboard, so he tightened the screws thus bending the side of the motherboard. So I'm thinking that maybe he shorted it out which would explain the odd behavior with the usb or could there be a problem which I missed.

Jam it back in, in the dark.