My iPhone stops working intermittently

OK, most likely something is touching the screen when you aren’t actively using it. For example, do you carry the phone in your pocket with the screen facing your body? If you are, you need to do 2 things: Go to Settings/Display & Brightness, and turn off Raise to Wake. Then, when the phone is in your pocket carry it with the screen facing away from your body so close contact with your body doesn’t activate the screen.

If you are concerned about protecting the screen, remember that a screen can be replaced, but if the glass back of the phone is damaged the whole phone needs to be replaced.

That is the message you will get if you enter the passcode wrong several times.

You will also see it of FaceID fails and you had previously entered the incorrect passcode.