Q: Iphone wont reactivate

So my iphone has been going in and out of reactivation, constantly turning itself on and off and rebooting numerous time in the day. It's now gotten to the point where it wont let me connect to wifi or sync to itunes to set it up. Every time it turns off I have to re enter Apple ID to get it as if its just been store bought! Tried syncing and it says on my itunes that it cant reactivate because there was an unknown error, and it now wont let me connect to any wifi.

Dont know what wrong, help, please!