I am trying to help my dad reset his Apple ID password, but everytime it asks for his pin to unlock his phone, it says it’s wrong even though it is not.

I’ve tried everything to help my dad reset his password that he forgot. But every different way we’ve tried it either freezes, or keeps saying that his pin to unlock his phone is wrong even though it is not. And then it blocks him from trying to enter it for an hour because it says he entered a wrong pin too many times. But it’s not wrong. We’ve tried 3 times now.