PC trouble booting after blunt trauma

Hello,

Recently one of my friends accidently kneed my PC after spinning in my computer chair. After this my Monitor went black and said to plug the PCIe cable back in. I did this, but the PC was failing to boot. There was a red light on the mobo (it's an Asus) so I shifted around the RAM. Now the PC seems to boot fine, the keyboard and mouse are on, but my monitor is showing no display. I checked everything inside and it all looks fine, but I am by no means the most experienced when it comes to computer repair. Any help or ideas of what may be wrong would be greatly appreciated, thanks.