To better assist you can I have your full model number?
Have you tried a Smart Hub reset? When you do that, don't set up Bixby, that should prevent the random pop-ups.
Tried that, but cannot because I cannot enter PIN, as I'm unable to get the numeric keyboard to appear. When I click on the colored dots button successively, no keyboard appears.
Then I would attempt a factory reset. If that doesn't work, service may be the next option. You're welcomed to send me a private message with the serial number so I can look into it for you!