My JG M4 airsoft gun wont stop shooting even when I let go of the trigger!?

I JUST GOT IT TODAY! even on semi auto it shoots full auto and wont stop shooting, I took out the battery, put it back and it did it again! the manual says if it shoots to long charge the battery, so I am, it i don't know if its just that its shooting to long or just not stopping, HELP ME PLZ!