iPhone 5 password lock turned on after upgrading to ios 9
After upgrading to iOS 9 my fathers iPhone 5 turned on its password lock and he cant get back in to his phone because he has never had a passcode. Its asking for the four digit password and he doesn't know it because he has never set up a password. Is there a way to recover his phone or revert it to iOS 8. I don't think he backed up his phone iTunes so Im not sure he can recover it but any help is much appreciated.
iPhone 5
iPhone 5, iOS 9.1