iPhone users who had their home button repaired by a third party suffered a nasty shock in recent weeks as their device shut down and couldn't be rebooted. This issue was caused by Error 53, something Apple originally said was a security feature.
At the time, Apple said, “This security measure is necessary to protect your device and prevent a fraudulent Touch ID sensor from being used."
Apple is now letting people with disabled handsets connect to iTunes to download an update to resolve Error 53.
It should be noted that fixing Error 53 doesn't restore Touch ID functionality. If you had your home button replaced by a third party, you'll need to go to Apple for a home button replacement.
Apple apologised for this issue and said that the error was supposed to be a "factory test." With the company currently facing a class action lawsuit over the Error 53 incident, it will hope that its recent steps help mitigate the damage.