I have an at&t iPhone 4s that is jail broken due to me using straight talk and needing mms. I want to back up and restore a sprint 4s from the AT&T 4s backup and it will complete and at last second it stays on a white spinning logo and black screen. Itunes recognizes but phone stays stuck. I tried to restore another sprint 4s I have and same exact thing. Tried backing up AT&T 4s again and restoring again and still no go. Could jailbreak be corrupting the backp? Any way to fix? I've never had problem and really need to keep my stuff.