Can't get my iPhone 6s to
Work. I download the back up - press continue and it flips to a
Screen which says 'slide to
Upgrade' but it's unresponsive and sits like that for hours. Finally got through to O2 chat - did what they suggested (soft reset - no joy, sync with iTunes - can't be done due to screen locked at can't unlock it) .. Anyone have the same issue? Thoughts on how to resolve?