I got determined AF to find a solution so I scoured the web again and stumbled across a different thread here on LTT. I must have missed it before. Well, long story short, I finally got it to work. Apparently my GPU needed some kind of firmware updater that's separate from GeForce Experience and regular Windows Update. With a simple update everything POSTs properly and I can get into BIOS no problem. I feel stupid that it was something as easy as an update, but honestly I had no idea this tool even existed. Thanks again to all who tried to assist. I listed the tool in case others might have issues as well.