The Device Display Screen Goes Blank
If your display screen goes dim or dark and looks like it is off:
Your device has been pre-set to turn off (sleep mode) if you haven't made any key activations for two minutes. The backlight on your display will become dim. You can touch the screen or activate a switch to turn the device back on (wake it up). If you do not wake up the device, eventually the backlight will go out and the display will be dark. Again, just touch the screen or activate your switch to wake up your device. It may take a minute or two to wake up.
If you need more time to elapse before the screen goes to sleep, you can increase the time to five or ten minutes by doing the following:.
Select the TOOLS 
key on the front the case.
Select the MAINTENANCE MENU key 
on your screen.
In the Auto Power Down option 
use the arrow keys to select the time you want.
Select the OK key 
in the bottom right corner of the menu.
Select the GO TO HOME key 
in the upper right corner.
You are back at the DIRECTORY page and ready to continue.