This is extremely unfortunate and frustrating. I have the same issue but, a harder issue. The PIN screen is there I never changed my PIN CODE but after a Samsung update the phone A12 shut off and re-started, now the phone is locked and I enter in my PIN and I get, " try again in **** minutes" the phone also went into Airplane mode and shut off WiFi connection and I can't turn it off ( Powerdown ) because it won't accept my PIN number. I have also been told that the only way to keep the phone active is to do a full factory reset and lose all data. The PIN is needed after a Power shutdown, and to get into settings. The fact that we can't recover our log-in from the SmartThings Find or Google FindMyDevice is completely ridiculous.
In order to reset the pin you will have to, unfortunately, factory reset the phone. However, you should not lose any data, as your phone is backing up automatically every night. After a reset, you would restore your backup. The fact that you can't recover your pin/password by another means is because the pin is contained entirely on the device and it is not known to your Samsung or Google account and it is a security measure to prevent anyone else from accessing your device or resetting your pin by those means, so it's not ridiculous at all.
I don't have an answer for why your PIN got garbled by the update, but I have heard of it happening to others.
You can still power it off by holding the power and both up /down volume keys together at once. Hold all 3 down until phone starts to come on. Should be in the factory reset screen if all goes well.
