Many iOS 7 beta testers will remember the mass panic when the beta expired last year. Devices were automatically restarting and coming up with the message “Activation Required”.
We have once again put together a simple to follow guide to fix this problem should it occur. The below guide will aid you with the upgrade process and ensure your device is updated to the final release of iOS 8.
1. Copy over your photos using Image Capture/iPhoto/etc.
2. Create a back-up of your device (if iTunes allows it!)
3. Make sure you have the latest version of iTunes then Download the latest iOS 8 firmware for your device.
4. Boot into recovery mode: How to boot Apple Device into Recovery (DFU) Mode
5. Hold down Shift (Alt on Mac) and click the restore button then find the .ipsw firmware file you have just downloaded and click restore. Please Note:- Everything on the the device will be deleted.
6. Restore from iCloud or using iTunes “restore backup”
*please use this solution with caution and ensure that you have a full backup of your device before attempting.