Q: after update phone says "slide to upgrade" but won't allow it

Phoneless? Join the club.  My iPhone 5 hasn't worked for 4 days.  All of us who have this problem need to somehow let Apple know that this is unacceptable and they should DO SOMETHING!.  To Apple support: pay attention to us!

Did you try the remedy that Apple suggested? Resetting your phone? Called AppleCare? Apple support isn't here so they aren't going to pay attention to you.