I wonder if it was an M-80, which I think is a quarter stick of dynomite, and would have maimed or killed someone and maybe a hole in the cabin. I would think some might call it a firecracker.
Early reports say that the deoce was strapped to his leg, and that it contained both a solid and a liquid.
It may be that he lit the thing but that the scuffle he had with the heroic passenger actually broke open the container
on his leg, thereby innitiating a flash burn of the explosive material rather than an explosion inside the containment of the device.What the pop could have been is the triggering part of the device which failed to explode the deice due to leakage, and a further flash burn as the wrestling spread the material around.
Both the perp and the hero were burned.Heros name not released. That bothers me.