I flashed a bad BIOS image and was able to recover my Rock Pi X via a very affordable CH341a programmer off Amazon.
I added some steps here:
https://wiki.radxa.com/RockpiX/bios
Once I flashed, I noticed the BIOS settings were at defaults (I was missing my EFI boot options, for example). So most likely, by flashing a raw BIOS image with a CH341a programmer, you can effectively reset the BIOS settings.