A couple of days ago I took a spare RC helicopter apart and took its four motors and 3.7v rechargeable LiPo battery connected to a pcb. I had been using it to power some LEDs on my bread board and it worked fine. Today I added a toggle switch within the same power buses on my bread board because I wanted to see if I could power the motors on and off. the motors would not work and the battery suddenly combusted. What could have happened? I'm guessing when I soldered wires to the same solder points as the battery something went wrong...