How can I downgrade from iOS 8.0.1 to iOS 8.0?
Apple released and quickly pulled iOS 8.0.1 on September 24, 2014 after users reported that the update broke their Touch ID and cellular data. Luckily you can still download iOS 8.0 from the evad3rs website and install it by following these steps:
1. Download the iOS 8.0 firmware for your device from the link posted above.
2. Disable Find My iPhone if you have it enabled (You can disable it under Settings > iCloud) and connect your iPhone to your computer with a USB cable.
3. Open iTunes and click the iPhone button in the iTunes navigation bar.
4. Hold down the Shift key (Windows) or Alt key (Mac OS X) and click Check For Update.
5. Locate the IPSW firmware file you downloaded in step 1 and click the Open button.
6. Click Update after iTunes verifies the iOS 8.0 file.