Computer not booting

I am unable to get my PC to boot up. It is very strange as my brother was trying to fix some sound driver issues, and when I show up the damn thing won't boot.

He has a Asus P8H67-M Pro motherboard, 650w PSU, GTX graphics card, and an i5 (Don't know all the specifics, don't think it is really necessary for this issue though).

I don't think he tinkered with anything for real, he was literally just at the desktop and took a peek into the BIOs without altering anything.

The motherboard light turns on, all the fans work normally, it' sjust I can't get it to boot anymore.

I have re-seated everything, checked every cable and made sure it was corrected right. Checked the RAM cleared & reset the CMOS. As a last resort to troubleshoot and figure out the problem, I literally took apart the entire PC and did a bare-bones setup with just the Mobo, CPU, PSU, and hard drive.

What should I do? Anybody know what the issue is here?

If a motherboard is fried, would the lights still power up and fans work correctly?

Any help is greatly appreciated! I really hope we can salvage this PC somehow, were in a really tight spot financially and really can't afford to replace many parts..