I attempted to upgrade my iphone 4s as it was having issues. Unfortunately, ios9 was just released. My phone is "frozen" in the trying-to-download mode (apple symbol with line under it).
I have contacted Verizon Tech support who had me try using iTunes. iTunes will update to a point and then ask for permission from the phone, but I can't because it is then back to the apple symbol with a line under it.
Any ideas how to upgrade without having to reset it to the factory setting and losing notes and messages?
If it is stuck, only hope is usually holding power and home button until iTunes and plug in symbol show and restor through iTunes. This erases everything though, so I hope you backed up recently.