-if- you can still get into the old one then I'd back it up to icloud post haste. If you already have then great.
Wipe the new one and my suggestion is that you don't completely migrate everything, but just the importants. Contacts, calendar, email.
Pull apps from the app store as you need them and don't migrate the 9000 never-used apps from the old one. (just a guess.)
It'll be faster and fresher and cleaner for the trouble, and almost guaranteed your problem will go away.