Set options for backlighting
On the home screen or in a folder, click the Options icon.
Click Display > Screen Display.
Do any of the following:
• To change the brightness of the backlight for the screen, change the Backlight Brightness field.
• To change the length of time that the backlight stays on when you're not touching your BlackBerry smartphone,
change the Backlight Timeout field.
• To stop the backlight from adjusting to lighting conditions, clear the Automatically Dim Backlight checkbox.
key > Save.
The screen turns off,