Dagur

If you are careful in the process, you will be fine. 

If you plug your drives in the same ports again and obviously don't break anything, there will be no issues.

As long as you don't damage your drives during the cleaning process, your operating system will be fine. 

You'll have no problems there. The only thing I'd recommend keeping and eye on is which SATA port your drives are plugged into. If you move them, you may need to re-adjust the boot order to get the system to boot. If you plug them back into the same ports, then no issues.

Maybe try disassembling your PC and reassembling it again and see if it works then?

1. Have you started off with the basics? Switched to another power socket, tried another power cable, the power button connectors are actually plugged in ect.
2. Are you sure there's absolutely no cables dislodged anywhere?
3. Do you perhaps have any other PSUs around?? 
4. I don't know what's the actual problem as it doesn't even start...
 
I think you should send me some skyr...the only thing I can think of currently that's icelandic...

You posted in the wrong section, there's a section called "troubleshooting".
 
What do you mean by " attempted to troubleshoot multiple times " ? It's very vague. Tell us what you tried.
 
Start with Mr.Meerkat suggestions, also check if the PSU is working by itself (Google "how to jump a PSU").
 
If the PSU work, check if the power switch on the front panel is the problem (you don't have to test the switch itself, you can start the PC by connecting the leads on the motherboard)

No need to be sorry it's all good. If the PSU died, be sure to get a reliable one and be ready for more damages, it's not uncommon for a dying PSU to kill other parts. Happened to me once.

Agreed, my friend's cx750 blew up and it took his gtx 770 and i7 3770k after him only owning it for 3 months...luckily corsair replaced everything plus gave him a RM850