I was in the same predicament: after software update on my S10+, my PIN would not unlock the lock screen. I had tried so many times that I got a warning that if I did not input the correct PIN in the next 5 attempts, a factory reset would occur. My biggest fear was losing all of my precious photos of my family, which I had stupidly not backed up (nor activated the Samsung Find My Mobile function).
THIS IS WHAT WORKED FOR ME:
I rebooted the phone in SAFE MODE: Hold both the power button and volume down keys until the phone reboots (you will see the Samsung logo); Release power button, continue to hold volume down until the lock screen shows up and SAFE MODE is displayed in the lower left corner. My PIN then worked and my phone unlocked!!!! Now I'm backing up all my photos/videos (and going to register the phone for the Samsung Find My Mobile remote unlock function, I hear that would have worked too).
Hope this works for you guys too.
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