Historically, it can be very hard to restore an older version of iOS 8 -- but in this case, Apple has fortunately made it rather easy. Just follow these steps to downgrade to iOS 8. An iPhone 6, ...

Is your iPhone frozen, locked on the Apple logo, or booting endlessly? Fix most iPhone issues with iOS System Repair without losing your data. When your iPhone crashes after an incomplete iOS update ...

Once they're fixed, simply follow our how to download iOS 10 guide to reinstall iOS 10. Hopefully you backed up your iPhone or iPad before you upgraded to iOS 10. If you did, then uninstalling iOS 10 ...