Keep getting a "System UI has stopped" message and can't shutdown.

[Android Central Question]

On a Galaxy S7 my apps keep closing (including the Settings App) and when I try to shut down I get a "System UI has stopped" message.
When I "Close app" (only option with the message), the phone starts unlocking and reboots. I need to use my PIN (not fingerprint) to start it, but everything is the same. Can't shut down and can't reset the phone and can't use any apps. Any suggestions?

 

[belodion]

Try Safe Mode.

If no go, perhaps you need to reflash the firmware.