iPod Touch Backlight Problem

About 3 weeks ago, my iPod Touch backlight randomly shut off everything else worked fine, but I had to put a light up to my screen to see it. I tried resetting it, restoring it, and basically anything else I could do, so I made an appointment at the Genius Bar at the apple store. The "Genius" at the store restored it on his computer, and the backlight worked fine. Just recently, my backlight randomly went out, again, and the same exact problem from before persists. I really do not want to take bi-monthly trips to the apple store, so it would be great if someone could help me. Also, if the apple employee can fix my iPod, I probably can too. I regret not asking him what he did, but I believe he did some sort of special restore to reinstall the iOS4 firmware. If anyone can help me or tell me what the apple genius exactly did to my iPod, it would be greatly appreciated