Question Tested working HDD (brand new) and SSD(fairly new) won't work or show up in BIOS. Sata cables and power cable tested and working. Thanks!

May 25, 2021
This is my first post here so sorry if i'm missing normal details.

So ive justed fixed my computer after spending 3 months working on a cpu warranty issue (finially got a new CPU), and now my brand new HDD (2TB Barracuda) and existing SSD (512 Crucial MX500) won't work or show up in BIOS. I also don't think the HDD is getting power as I cannot feel it spin up but I cannot be 100% sure.

Both drives were tested on my laptop with an external SATA enclouse and seem to work fine. Tested the SATA cables on my other computer and all seem to work fine. PSU is brand new as well, the drive power cable is plugged into my case and provides power, so appears to be working fine. Though I replaced it with another cable (spare that came with the PSU) and no dice. Tested two drives from my other computer (with their sata cables), they don't work either.
I just don't know what could be wrong, I have replaced and tested everything to the best of my ability and I cannot find what is wrong.

Weird side note: My OS is running of an M.2 which works fine, but does not show up in bios either. It does show up in device manager, where none of the other drives do.
Any assistance would be dearly appreciated, just so fed up with trying to fix this computer, which has already taken months and a decent amount of money. Thanks in advance.

Also had my SSD plugged in for a bit, noticed it was getting warm so assuming it was getting power. Another interesting thing was I was getting audio pops and system lag. Did a DPC check and latency was nearly 40,000 (should be around 20-1000), unplugged my SSD and it fixed the latency.