Downgrading iOS 9 public beta to iOS 8.4 is quite easy. I installed the public beta just to see the new changes in iOS 9 but I’ve been having some serious battery drain. I can’t complain, it’s called a beta software for a reason.
Here are the steps:
1. Backup your device through iTunes. It’s not enough to have just an iCloud backup.
2. Download iOS 8.4 for your device from this page. Be sure you choose the right one for your device.
3. Connect your phone and start iTunes. on the phone summary page, hold the SHIFT key on your keyboard and click the Restore button.
4. Select the IPSW file you download earlier from the download location.
5. Accept to restore when the prompt message comes up.
6. The process should take about 10 minutes or more.
7. After a while, the process should complete and your phone should show this if you have the right carrier SIM inserted:
8. It’s all done now. All you need to do is choose your previous backup and restore:
Wait till it’s done before disconnecting your iPhone. This may take a while depending on how big your backup is.
