A couple of things:
There seem to be a sequence of adding/removing fingerprints that leaves the unlock screen funky, so no pin entry keyboard is shown. I don't know how to unlock my phone now. Fingerprint unlock seems to work 'for a while' and then does not. It is a phone for playing, so I'll end up resetting it again. I'll try a usb keyboard before resetting.
The latest ota upgrade left the phone on the Samsung banner screen. I re-installed from zero to recover it (recovery mode worked, so other strategies might have worked)