Most probably not the battery nor the receiver fault. Human error. I'll bet you had a generic connector on the battery (will plug in either way) and you plugged it in backward. Futaba receivers have what I call a design flaw, on the battery slot only, the center conductor is tied to the signal (outside lead) by printed circuitry on the receiver printed circuit board. If you plug a battery in backwards, instant short which results in charred wires, lots of smoke and melted insulation. In my opinion, this is the dumbest thing Futaba has ever done. Had you plugged the battery into any other slot, no harm would have been done--the system would just not have worked. If you were lucky, the receiver wasn't harmed although it might have been. Take the board out of its case and look for burned out wiring at the battery connector slot. If all looks okay, you are probably safe to use it.