Windows 11 upgrade failed and now I can’t boot

Stuck in Windows 10 Upgrade

My computer seems to be stuck in a Windows 10 failed upgrade loop. I was running fine on a beta version of Windows 10, and then I came downstairs one morning to see it repeatedly booting, attempting to repair, then rebooting. The steps I’ve taken to diagnose are:

• Attempting to boot off a USB drive (with all drives disabled in BIOS) – this fails at the point of the blue windows screen
• Attempting to boot the machine itself and getting into “repair/safe mode” using F7
• Looking at the BIOS for obvious failures (e.g. RAM that should be there is missing) – nothing obvious is wrong.

I am fairly certain the build version was 9926. For many months, the system would attempt to upgrade, and then say “it failed” for some reason and roll back.

Suggestions for next steps?