does he have a 3DS or a DS. If he is trying to play it on the DS it will not work. If he is trying to play on the 3DS, try blowing on it or message gamefly about broken game in mail and they will send you a new one immediately. Then return broken game to them like any other game you return.
well you should probaly send it back to get a new one they will send one back real quick and throw something in for your trouble tell your 8 year old i said srry that it didnt work and tell him people cant take care of games best of luck