You should take everything apart and clean it, either that or blow in the cartridge three times, slap it on your knee twice ,and then quickly insert it and press power, reset, power, power.
Another trick that works almost everytime(Seriously) is to insert the cartridge and push it down into place but not turn it on. Take a pen or pencil and rub it back in fort quickly but not to aggresively in the thumb grip part of the cartridge making sure that it is hitting both sides of the grip area. After you do that a few times you should be able to turn it on and play.