In this video from soxfan647 we learn how to access the system config screen on the iPod Nano. First reset it by holding the center and menu. Now when it resets, hold center and rewind. This is used for testing the LCD. You can click the center button to rotate between different colors of the LCD screen. This will only work on click wheel iPods. You can even use the click wheel to go through different screens in this mode as well. This will look different on different styles of iPods. To get back to normal just hold center and menu.