In case anybody is still interested - I did actually try a return to the factory image.
(I have a couple of these devices. I am still running Debian Bullseye on 4.9.266 on my production unit 
)
I left the GoldenImage partition untouched, that’s why this worked:
mount /dev/sataa18 /mnt/
echo '5:F:2:;' > /mnt/bootConfig
umount /mnt
reboot
The unit updated itself to 7.16.0 within minutes. I am now waiting for 8.x.y to have a look at everything else.
