Ya, that's a tough decision. I wouldn't update the main to F10 unless you plan to abandon further troubleshooting.
I'm curious. If you return the BIOS switches back to defaults (dual) and press ALTl+F10 does the system prompt to copy main to backup?
You don't have to proceed if this isn't clear. You can exit by pressing/holding the power button. You'll have to decide if you want to attempt reflash. You should still be able to use the switches to boot from a working BIOS.