iCloud locked my dad out of his phone

We just got new phones and while logging into iCloud to transfer information, my dad messed up on the login information. This caused the phone to “lock” him out. It has the login screen and had a loading. This is after it said he had been locked out of iCloud for security reason. This is the new iPhone 12 pro. The picture is of the screen he has. You can’t even turn the phone off. What do we do?