Chosen Solution
I have an iPhone 6s and I replaced the lcd, when I powered on the device everything was good for about a day. It worked fine, suddenly a message appeared “unable to setup touch ID”. Made a hard reset but nothing, I restore all setting but nothing, replaced the lcd but nothing, restore to factory setting but nothing. Then I decided to install the broken original lcd but again NO TOUCH ID. I have done everything I read in other forums, I inspected the connectors in case of damage but Iooks fine, then I tested the lcd in other iPhone 6s to see if this is going to work there and worked just fine in other iPhone.The touch ID menu IS NOT GREY, I can select menu “add fingerprint” but then returns message “touch ID fail” I’m desperate, I don’t know what to do and I really need the touch ID. I use it for some account sites and bank sites. This strange behavior I don’t know what to do.please I need advice from someone had fixed similar issue. Thank you
Take a closer look at the Home Button and the HB flex. There might be some damage such a slight tear or damaged pin. By trying multiple screens, you have probably ruled out the home button link flex (that runs beneath the backlight) Otherwise, the problem may be with the MESA circuit as that is the circuit that powers the TouchID.
I solve this problem by reseting this phone from dfu mode. Made a clean IOS installation and worked fine
The only thing that I can suggest was to go back to the technician who service your iPhone 6s and tell him/them your current issue. Common issue for this usually are disconnected wirings, or improper assembly of the phone components.
