[Hectic]

Does it have a nunchuck battery or a mini (rectangle) type.
As far as i can google the battery goes in the handguard. Pull on the round bit (that is between the handguard and reciver) it will likely be hard to pull (pull it towards the reciver) and you should be able to remove the lowwer handguard and see if the plug is there.
Or you can pull the stock off. Instead of pushing the lever that adjusts the stock pull it down and slide the stock off and you will see if the plug it there.