Put Working PC in Case, Now Won't POST

So, a few months ago, I built a PC for the first time but never put it in a case.

My specs were:

ASUS B85M E/CSM Mobo

Core i5-4440

16GB DDR3 RAM

EVGA GeForce GTX 660

The night before last, I finally bought a case for the PC and tried to put it together inside. Several things went wrong during, including: I accidentally dropped the CPU fan onto the MOBO while trying to install it properly so it wouldn't fall in the case.

My PSU was too big for the case (had no idea that I would need to measure PSU length), so I ziptied it to several places in the case so it would stay put.

I noticed what I thought was a broken part of my MOBO speaker (the thing that makes noises for BIOS beeps and stuff) and pulled it off the MOBO, then got a spare speaker out.. Apparently it was actually the jumper you're supposed to take off to clear the CMOS memory, but I didn't know that.

When I got the computer together, it wouldn't turn on or POST. The PSU was making a very quiet squealing kind of noise that would get more noticeable when I held the power button in. The fans would not turn on, bit the lights on the MOBO and PSU indicating power recurving we're on.

I tried reseating RAM, booting without my GPU, reseating GPU, booting without HDD/mouse/keyboard/RAM, etc.

I inspected both MOBO and CPU socket for damage/bent pins and found no signs of anything wrong with them.

I tried an old MOBO that was not confirmed working with all of the above troubleshooting steps and got fans running but still no POST or BOOT, and the squealing noise from PSU was no longer there.

I tried the PSU in an old Core 2 Duo machine and it booted just fine with all parts plugged in, including GPU, so I'm pretty sure I can rule out my PSU bieng the problem. The PSU was not making the weird noise here either.

I found out late last night that the thing I'd removed was a CMOS memory clear jumper thing, and put it back, but didn't get around to attempting to boot again because I needed sleep to be alert at work today.

My question to you is thus: Do you think it likely that the missing jumper to clear CMOS memory was the problem? If so, could I have damaged the MOBO by attempting to boot with it missing?

**EDIT: It was my PSU. Thanks for the help you guys have given me tho!**