Sometimes one may be faced with an apparently dead clearo/carto/tank. The culprit could very well be the threads (try loosening it slightly on the battery) or it could be the battery connection. Have a look up the bottom of your container. You'll see a collar with a circular machined post inside. That post can move a little, i have used a precision screwdriver to lightly move it outwards and better center it. Viola my device is working again. This may work for you. Cheers!