Sounds like that cartomizer has a short. I would recommend not using it. Did you stick anything into the cartomizer (like use a syringe to fill or something? If so then that could have caused the problem - there are wires in there you can hit with a syringe.
One time I got a bit too energetic with something pointy trying to clean some
juice sediment that was clogging the bottom hole area of a carto, and somehow I pressed two wires together that made it bypass whatever was moderating the resistance and the carto got very hot.
Or maybe it is just a defective carto.
Do not use the hot carto - it could damage your battery.