“iOS 8.0.2 is now available for users, it fixes an issue that affected iPhone 6 and iPhone 6 Plus users who downloaded iOS 8.0.1, and includes improvements and bug fixes originally in iOS 8.0.1. We apologize for inconveniencing the iPhone 6 and iPhone 6 Plus users who were impacted by the bug in iOS 8.0.1.”
Follow these steps to reinstall iOS 8.0.
- Make sure that you're using the latest version of iTunes.
- Connect your iPhone to iTunes.
- Back up your iPhone in iTunes on your Mac or PC. iCloud backups won't restore to earlier versions, including iOS 8.0.
- Download the file below that corresponds to your device:
- iPhone 6
- iPhone 6 Plus
- Select the file you just downloaded by doing one of these in iTunes:
- Mac: Press the Option key and click Check for Update.
- Windows: Press the Shift key and click Check for Update.
- Press Update to install iOS 8 on your iPhone.
Source: Support Apple via Mac Rumors