The latest update for the Samsung Galaxy S10 and Galaxy S10+ locked its users out, requiring them to enter a PIN and restarting repeatedly no matter what they entered. Unfortunately, it looks like performing a Factory data reset is the only solution available for those affected by this issue.
https://www.notebookcheck.net/Samsung-Galaxy-S10-and-S10-got-an-update-that-locks-users-out-randomly.427321.0.html
I had this same issue present itself just recently on a Galaxy Tab S4. My PIN didnt work, my remote device access didnt work, I couldn't use the software to restart because even that asked for the PIN. After getting the same responses from Samsung customer service (either factory reset myself or send to a Samsung service center for the same), I figured out how to force a hard reboot. Just holding the volume and power button shut down the device. Upon reboot everything worked fine again.