Here's the deal: I have a Genesis Game Genie (brazilian one) that came with the Megavision a friend gave me. I think I only used it once, since I'm not that much of a fan of the Game Genie premise. It's been lying there ever since, unused.
Still, I read here somewhere that you can use it to circumvent region locks and stuff like that. Is it the case (the Megavision already has a US/JP key, but there's always European carts)? Besisdes that, is there another usage for it that I'm not aware of?
Noob P.S.: What's the little key (which lights the green led) on it for?