first issue is my touch ID. it hardly recognize my finger, and it's really difficult to purchase item in appstore. is there a way to change the finger print device only? second, sometimes my iphone got hang in the screen. screen wont touch, but i can still press home button, can talk to siri, and tell siri to do thing for me. but i cant touch the screen, and i cant force restart by long pressing my lock button. i've been pressing it around 20 second but nothing is happening. any suggestion what should i do?