If you don’t use the phone for a while, the screen and backlight will turn off to conserve battery power. To unlock the phone:
Turn the screen on.
Press the Power/Lock Key on the back of the phone. The default Lock screen will appear.
Avoid covering the proximity sensor when turning the screen on. Doing so, immediately turns the screen off.
Quickly double-tap the center of the screen (KnockON).
From the center of the screen, swipe in any direction to unlock it.
To use a shortcut, swipe the shortcut icon at the bottom of the screen in any direction. The screen will unlock and launch the application.
The default Lock screen simply locks the screen to prevent unintentional actions. For more security to guard against unauthorized use, you can set an unlock requirement (such as a pattern, PIN, password, or face recognition) that will need to be entered to unlock it.