I remember the original 2.x.x were private invite firmwares that the Bond team pushed, hence me asking Chris Merck if he had time and ability to look into something like that. (Edit for clarity: Later developments made this automatic / v2 became public firmware rather than beta – but that doesn’t seem to be functioning nicely in your scenario.)
Once you’re on some version of V2, then the world is your oyster up to the point that Gen 1 hardware got V2 updates – you can even directly upgrade the firmware to known hashes.
I do have a friend that has one of my old BD serial / Gen 1 hardware units. I’m curious if he will let me take it back for a bit to factory reset and see if I can sniff out any firmware hashes if it can successfully update.
I do hesitate if there isn’t a known recent success of v1 → v2 updates though, since I’d hate to hand him back a hamstrung device which cannot restore a (v2) backup… 