Reminds me of a funny story: A few years back on a visit to Beijing, was hustled on a street corner to purchase what appeared to be a brand new iPhone (a 7, if memory serves), for a ridiculous price. The seller handed it to me to play with, and proudly demoed the fingerprint unlock feature. The interface looked flawless (given that it was Chinese). Naturally, it was a fake. Doing a hard reboot brought the green Android bucket at boot.

As for the unlock feature, it took the user through all steps of fingerprint setup only to work with any finger (or anything else warm toughing it, for that matter).