How do you restore if the unavailable sign is still there?
someone tried to unlock the phone now its blocked and showing "iPhone Unavailable"
what to do?
iPhone 11
If you forgot the passcode on your iPhone, or your iPhone is disabled or unavailable -
Click on the link for instructions on how to reset your passcode without a computer if you have iOS 15.2 or higher.
If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support
Click on the link for instructions on how to reset your passcode using a computer.
If you forgot your iPhone passcode - Apple Support