Changing the Backlight Percentage on the V5 Brain

Make sure the V5 Robot Brain is on

Turn on the V5 Robot Brain by pressing and holding the Home button on the brain.

Select the Settings icon

Tap on the Settings icon as highlighted by the red rectangle.

Select the Backlight setting 

Tap on the Backlight setting as highlighted by the red rectangle.

Continue to tap until you reach your desired setting.