Touch ID Setup Failure

I cannot get the touch ID feature to work on my iPhone 5s. During the setup of the touch ID it immediately fails and never allows me to place my finger on the sensor to capture my print.

The back story on this phone is that I purchased a slightly damaged black iphone that had a cracked display and bend case (corner). The phone functioned fine, as the damage was only cosmetic. The touch ID feature worked flawlessly. I decided to purchase a donor phone off eBay that was white (my preferred color). I swapped the logic/mother board out of my "damaged" phone and put it into the white phone. The new phone worked well, except the touch ID wouldn't setup. My research pointed to the problem being the home button (touch ID sensor) from the white phone was not compatible with the logic/mother board from the black phone. Apparently the touch ID and A7 processor are paired together when phone is manufactured and a replacement touch ID sensor will not work.

Knowing this, I purchased another donor phone that was in pristine condition and black in color. I swapped the logic/mother board out the the phone again and replaced the home button (touch ID sensor) and lighting flex into the new black phone. So the current phone setup has the originally paired logic/mothe board, home button (touch ID sensor), and lightning flex cable. Despite taking great care to ensure no parts were damaged and everything was installed correctly the phone still fails touch ID setup.

I have repaired several dozen iphones and I am very confident that no parts have been damaged during my repairs. I have tried restoring phone to new and the setup for touch ID still fails. I have tried both 8.1 and 8.1.1 ios software...no luck.

I am at a loss. Did exposing the A7 to an unpaired home button permanently disable touch ID forever (even after reintroducing the originally paired sensor)? Is there a security feature the permanently disables touch ID when a non-paired sensor is installed?

I visited my local apple store and talked with a "genius." I was told the touch ID feature should work, but I wasn't convinced that he was confident in his answer. Any ideas?