Greetings Bluebell12341399,
Thank you for taking the time to create an Apple Support Communities account and then posting your question here!
First let me say that I know how frustrating it can be when an unexpected issue arises during an update, but I want to assure you that we are here to help and committed to helping you resolve this. :)
You have done a great job troubleshooting already by working through first steps located in this article. I understand that you have already restored from a backup, but you still see the Slide to Upgrade message on your iPhone’s screen.
To continue troubleshooting, it may be necessary to follow the remaining steps from that article and set up your iPhone as a new device once the restore is complete.
If you still see the Slide to Upgrade screen after completing the steps above:
- Restore your device. If you don't see your device in iTunes, or your computer won't trust your device, press and hold both the Sleep/Wake and Home button for at least 10 seconds, until your device restarts and appears in iTunes. When prompted, choose Restore.
- After the restore is complete, set up your device as new.
Please reply and let the community know if these steps helped you resolve the situation. Your input is very valuable and we look forward to your continued involvement!
Cheers!