Fully updated iPhones can be permanently bricked after undergoing unauthorized repairs.
iPhone 6 owners said that their handsets stopped working after updating to iOS 9, according to The Guardian. Users reported that their phones were bricked after the software upgrade and that attempting to restore the phone led to an error message.
This problem affects phones that have had their home button fixed by a non-Apple repairman. There are also reports that this error affects users who ignore hardware damage and continue using the device without repairing it.
An Apple spokeswoman told The Guardian that the error message occurs when unauthorized technicians use replacement parts that can affect the touch ID sensor. Third-party repairmen can cause a failure where a customer's fingerprint data are unlinked from the home button sensor on their phone. Authorized repair service providers can fix the hardware without causing this issue.
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A tech expert told The Guardian that this is an extension of Apple's dislike of third-party modifications and repairs to its phones. Apple's position on unauthorized software modifications (a.k.a. "jailbreaking) can cause security vulnerabilities. The company reserves the right to void product warranties and refuse to service jailbroken devices.