Hi there and welcome
Can you please connect the phone to your computer and then open itunes. If you do not have iTunes on your computer, please download it from
Once open, and the phone connected, it should pop up with a message that it needs to recovery the iPhone.
Do this and once it has completed, tell me if it is now functioning correctly please.
I can also do these steps for you, and have made a request via Additional Services. This is optional, and if you choose to do this, I can, with your permission, remote into your computer while you watch and do all these steps (and deal with any problems that arise during them) for you. Or if you do not choose to take this service, we can continue here. This is no problem at all. Just let me know please.
Else let me know the results please.