How do I rest iPhone to get rid of the the message “IPhone is unavailable” try in 8 minutes
How do get my iPhone out of the screen that says iPhone is unavailable” with only Emergency call option
For the iPhone Unavailable message, see the information in How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support including the following:
From your device's Lock Screen, try entering your passcode until the "[Device] Unavailable" screen appears and your device asks you to try again later. When you're able to, continue trying to enter your passcode until the "Security Lockout" screen appears and you get the Erase [Device] option in the bottom corner of the screen.
If that option is not available, you will need to use a computer. See: If you forgot your iPhone passcode - Apple Support