Laut IGN muss man nur dieser kleinen Anleitung folgen:
"Gently push the tip of the screwdriver against the right side of the silver Game Boy Advance label on the back of the system. Watch the sticker -- you'll notice the label push inward and reveal a circle. This is the hole where the potentiometer is in. You'll have to pierce the label with the screwdriver to reveal the hole. At the bottom of the hole is what you need to turn with caution with the tiny screwdriver. Watch the screen as it slightly dims and darkens as you turn the potentiometer (or pot for short)."
Ausprobieren auf eingene Gefahr ;-)