Don’t update if you’ve had your phone repaired by someone that’s not Apple
You can file this into the “thank god I use Android” column: the Guardian is reporting that users have bricked their iPhones right after upgrading to iOS 9. Apparently the problem has been traced to a security measure implemented by apple via Error 53. The idea is that a device is rendered inoperable if the phone detects that the TouchID module which is housed in the home key has been replaced by a non-Apple compliant part to prevent data theft and loss. Unfortunately, if you’ve had your iPhone repaired through a third party that did not use official Apple parts, your phone will be bricked and affected by Error 53 when you update to iOS 9.
The problem isn’t just affecting people who replaced TouchID modules – even people who have gone in for screen replacement in third party shops have been hit by the issue as well. Once Error 53 hits your phone, they only way to fix it is to send it to Apple, and there’s no guarantee that your phone’s data will be recovered if you do get your phone fixed by them. Also, you’ll have to pay for the repairs yourself too, so there’s that.