The iOS 8.0.1 update was released a while ago, and though it fixes a lot of lingering bugs, but the update is a nightmare for users who are in the ownership of an iPhone 6 or iPhone 6 Plus, as it breaks cellular network capabilities of the devices along with Touch ID. But luckily, there’s a fix for those who have updated to iOS 8.0.1 and are left with a $650+ paperweight.
Without wasting a minute, here’s how you can go through the downgrade process. And the best part is: it doesn’t take that much time either.
How To Backup Using iCloud / iTunes
Since we’re doing a clean restore (downgrade) to iOS 8, therefore you’ll lose everything on your device, hence making a full backup of your device should be your first port of call.
Navigate to Settings > iCloud > Backup and hit the Back Up Now button to backup everything to iCloud.
Alternatively, you can use iTunes to backup your device. Connect your device to your Windows PC / Mac and launch iTunes, then click on This Computer under the Backups pane. Then click on Back Up Now. This might take a while depending on how much content you have on your device.
Restore Using iTunes
Step 1: Download iOS 8 final IPSW from here. Download the correct IPSW file catered for your iPhone 6 or iPhone 6 Plus.
Step 2: Once the download is complete, connect your iPhone 6 / 6 Plus to your Windows PC or Mac via USB, and launch iTunes. But before proceeding forward, turn off Find my iPhone on your device by navigating to Settings > iCloud > Find my iPhone and turn it off.
Step 3: Select your iPhone from the left-hand side column in iTunes.
Step 4: While holding down the left Option key on your Mac (or left SHIFT key if you’re using Windows), click on the Restore iPhone button.
Step 5: Select the IPSW firmware file you downloaded in step one and let iTunes going through the restoration process.
When the restore process is complete, you’ll be back to iOS 8.0 sans the cellular and Touch ID issues.
We’re certain that Apple will come through with an official fix for this blunder in the form of iOS 8.0.2 in the near future, but till then, this fix is your best bet.