I pretty consistently get the message, “unable to activate touch id on this iphone” if I connect the battery before connecting the group of cables in the upper right corner. It seems that if those are reattached while the battery is plugged in I see the touch ID error. Connecting the battery after connecting the upper-right corner group of cables has consistently helped. YMMV of course.
I consistently was receiving the message, “Unable to activate touch ID on this iPhone.”
Pretty consistently I noticed that if I connected the group of cables in the upper-right corner before connecting the battery cable this error goes away.