When your i Phone reboots, it should now be selectable in i Tunes.
Restore your device to factory settings and then set your i Phone up as new.
Although backing up and immediately restoring to that same ‘buggy’ backup seems redundant, it actually flushes out the weirdness and when the phone boots again it will be able to complete the upgrade. Update: Apple has now provided additional recovery steps.
However, before the first step, try logging in to i and removing your device from the Find my i Phone portal.Again, you lose all your data this way but it’s Apple’s latest advice on how to resolve the ‘Slide to Upgrade’ bug.Apple has also announced a software update is coming soon to address the ‘Slide To Upgrade’ i OS 9 bug.For those cases, here’s another approach to manually update to i OS 5.In some circumstances, your frozen i Phone will be able to detect the protection has been removed and allow you to continue as normal.
If this does not help, call Apple Care or visit an Apple Store.