After voice asst activation samsung galaxy s7 won't work.

[Android Central Question]

Activated Voice Assistance in a Galaxy S7. It announces the time and says to use 2 fingers to swipe. Do the swipe and then goes to password. Instructs have to enter at least 4 digits. Enter my password as it announces each key typed, Instructs to double tap to activate, I double tap, but then screen turns off.