[sushicake]

Check and make sure that charger of yours can charge your type of battery in the first place. Check if your battery is either an NiMh or a NiCd and if your wallcharger can even charge it at all. Most if not all crappy black generic wallchargers cannot charge NiMh unless specified and force charging a NiMh battery on a NiCd charger will damage your batteries! cause if you're batteries are sparking when you're plugging them in you're definitely doing something wrong.

Also I'm guessing you have the CA Mp5 with the sliding stock, there is no fuse on that specific model so you dont need to worry about if. But if it turns out it does then it looks like a white elongated pill just open her up and check if its burnt out. Also the fuse is never inside the guns body it's always near the battery connectors.