Why would the home button work, but not Touch ID?
I own a small Apple repair business, and have done a large number of iPhone screen repairs... everything from the iPhone 3G up to the iPhone 5S. I have only done a handful of 5S repairs thus far though, and haven't had any issues until now. The problem I'm having with a customer's phone is with Touch ID. Now, I'm fully aware that the home button flex cable that ships with a 5S is unique to that particular phone, and cannot be replaced while still preserving Touch ID functionality. Repairs don't generally make me nervous anymore, but 5S repairs do because of this....so, I'm extremely careful.
With this particular 5S, I successfully replaced the screen, only to discover that the part was faulty (defective digitizer). However, I know that Touch ID was functioning after this first screen was installed because I did test. I then installed another new part, everything went well and the part tested fine this time. I did not specifically test Touch ID functionality, but I do know that the home button was working. I've always figured that if the home button is working, then Touch ID is going to function.
The customer called me today to let me know that Touch ID is indeed not functioning at all, but the home button is. This seems very strange to me, and the only thing I can think of is that I didn't get the home button flex cable connector properly seated when I put everything back together. I will have a chance to open the phone back up tomorrow, but in the mean time I was trying to do a little research on potential causes for this as well as potential fixes. Of course, my hope is that removing the bracket, disconnecting, and reconnecting the flex cable will do the trick. Of course, unfortunately the simple solution isn't always the answer.
Numerous searches on here, Google, and other websites have turned up nothing with regards to this problem. Everything I can find relates to the unique relationship between the original home button cable and the motherboard, but that's it. I did find one person that had Touch ID functionality, but no home button functionality. Similar but still different enough to not be too helpful.
So...any ideas out there? Has anyone else come across this issue? Thanks in advance for any help!