TLDR: iPhone touch ID error can be caused by a hardware issue and the device may need repairs.
One day the Touch ID feature on my iPhone 6 stopped working. Attempting to change the phones settings to enable the Touch ID functionality would show the following error: Failed – Unable to complete Touch ID setup. Please go back and try again.
I followed these steps to troubleshoot this error:
- Back up the iPhone to iTunes. Then erase all content and settings to start with a fresh install of the iOS software. Then tried to set up Touch ID during initial phone set up was not successful. This points to a hardware issue.
- I called Apple support and talked to a technician. After confirming that the software had already been reinstalled the tech suggested that I visit the genius bar. I was able to get an appointment for the same day.
- The Apple genius bar tested my phone and confirmed that the Touch ID error was due to a hardware issue. Their recommendation was to replace the screen digitizer, the cost would be $110 and it would take about an hour. If the repair did not fix the issue with Touch ID there would be no charge for the repair.
- The apple genius to test my battery which is running at 80% of its initial capacity. The phone is about 1 1/2 years old.
My findings concluded that the Touch ID unable to set up error is caused by a hardware issue. Apple can attempt to fix the issue by replacing the front screen digitizer but the repair is not guaranteed to solve the problem.