I wrapped a .51 ohm coil and installed it on the rda section of my subtank. I then pressed the fire button for a few seconds to heat the coil up after which I compressed the coil with my ceramic tweezers. I pressed the fire button a second time and the coil began to heat up then stopped. The display screen read high temp then shut off. At which time I noticed smoke coming out of the device. I ran outside and pulled the battery out and sat everything outside to cool down. The battery had not vented and the smoke was coming from inside the kangertech subox itself. any ideas on what happened? This is not my first time building on the rda section and I always test the resistance of my coils on a ohm reader and the subox before firing them.