Edit: I panicked, went to open a support ticket for FP4, and read that maybe Safe Mode could fix the problem. I rebooted into SM, the sensor was working ok, rebooted in normal mode again, and it’s working again. I have no idea what might have happened.
Today I rebooted my Fairphone 4 and this materialized a software update that somehow was pending (I was not aware of it, nor do I remember when was the last time I had turned it off). As a result, the fingerprint sensor has stopped working: my finger is still saved in the phone, but the sensor will just not reach. This means that I can’t access some critical banking features.
The phone has been working perfectly fine for half a year, until today.
How can I debug or troubleshoot this issue myself?