How to Adjust the Screen Brightness of the Wii U GamePad
What to do:
From the Wii U Menu, press the HOME button.
Tap "Controller Settings" on the left.
Tap "Settings" under Wii U GamePad.
Adjust the screen brightness by tapping the + and - icons.
When you are finished, tap "Back" or press the B Button.
Tap "Back" or press the B Button to return to the HOME Menu.
Tap "Close HOME Menu.