iPhone 5s, iOS 8.2, Fingerprint sensor is suddenly not working.
The clip that holds the ribbon cable plug in 
Place on the home button has come lose allowing the plug to Free float in the socket. 
Open the phone being carful not to open 
It too far and snap the clip back in place,
And never subject your phone to excessive 
Vibration like a bike Handlebar cradle. 
Close the phone and you are good to go.