Press and hold to turn on or off airplane 
mode, control vibration, restart, or shut down. 
  Press to turn off or on the screen display. 
Press or hold either end of the key to turn the 
volume up or down. 
  Touch to return to the home screen from any 
application or screen. 
  Touch and hold to use Google Search. 
  Touch to go to the previous screen. 
  Touch and hold when the screen is unlocked 
to use voice command. 
Touch to see recently used apps. 
  NOTE:   
The Home key, Back key, Recent apps key and Menu key are 
located at the bottom of the screen. You can touch    to hide 
them, or swipe up from the bottom to restore them.