I had sort of the same thing happen recently. I took a couple of vapes from my mod locked the ring and set it on the counter and went to work. When I got home something smelled burnt checked and somehow it was firing slowly for 9 hours. It burned the connect pin in the RSST atty was all, battery wasn't hot. I decided from now on to pull the battery on all of them if I'm not using. Actually it's working quite well as the adjustment is usually the atty connection and just dropping in a battery work 90% of the time.
Glad you and your girlfriend were not hurt, dispose of the whole unit and get something else.