Caged, were you ever able to get a hold of the vendor for refund or replacement? I'm wondering where you got yours from...
Also, what kind of atty were you using, what build, settings, battery etc?
I got a new RBA tank system yesterday and think I may have had a similar experience to yours. It seemed like it continued to fire after releasing the button. This was my first time building on a RBA tank system...Orchid V3...I quickly unscrewed it and removed the battery...the battery wasn't hot, and the device didn't feel hot that I can remember, but I decided to take the tank off and use something else. It was a .2 ohm build which is lower than I normally go on this device. I don't think I damaged mine, and it seems to still be working fine (currently using Magma RDA @ .9 ohms), but maybe if we put some info out there, others can prevent damaging theirs. At this point, I'm staying away from super low ohm builds on the BEC Pro...I also put a small rubber band between the 510 connection ring and the plastic. If I'm not mistaken, Smoktech recommends mech mode for low ohm builds on this device, but they shouldn't rate it down to .2 ohm if it can't handle it in regulated mode...
Saw in another thread that you got the Cloupor ZNA 50...that thing looks BADASS! Hope that it works well for you