I'm running into some trouble with my unit. I can't seem to get a good connection with any of my batteries. The spring on the bottom seems to move either to far to the side or get stuck down so by battery isnt popping up enough to make a connection. When I do get a battery to connect, the unit tells me it is dead about half the time. I'm only getting about 2 hours before it tell me they are dead. I do chain vape, but I usually can get about 4 hours with my Trustfire 14500's. I know my some of my batteries are not dead when I put them in, they were charged yesterday. Any fixes or anything, or did I get a defective unit?