Question Help! My PC isn’t working.

Jul 16, 2020
So I recently upgraded my pc to a Ryzen 3900x and an 8 terabyte secondary hard drive (to my 500 gig ssd).
I had enough parts left over from upgrades to buy a couple of parts and make a second PC as well.
After troubleshooting with the second build, I found the GPU wasn’t working (MSI 1070 8G), so I decided to put it in my main machine to see if it works (MSI 1080ti 11G).
Long story short, it didn’t work, and I booted to a black screen with an unmoving underscore. Thinking this issue was unfixable: I took out the 1070, and reinserted my 1080ti.
Then I tried booting.

Now my system is stuck on that damn black screen. I’ve tried getting to bios, using a windows boot media (USB), and unplugging my hard drive.
Nothing I’ve tried works, and now I’m stuck with two non-working systems. My PC was working just fine, nothing was wrong.
I’m either blaming the 1070, or the windows update (the last thing I did with this computer).