AUG shoots continuously

Hello, people! I am calling to anyone who knows his electrical field.
I participated in a national event and I had to abandon from the first day.
The story is that when the rain caught me in a mission, my AUG started to fire on it's own, even with the safe on, and there was some smoke also (possibly from my colleague's cigarette, but it didn't smell like tobacco). So something, somehow send continuously electricity. It's not the trigger, because the slides are not touching, so I think it's the mosfet. I let the gearbox at sun until the metal was burning, so it's not about water still being inside. I wouldn't dettach the mosfet to try without it. From what I saw, it is sealed with a heat shrinkable tube, so the water shouldn't affect it. Or...?
So what do you guys recommend? To still detach the mosfet? Should I open the gearbox to look inside at the trigger's contacts? Thanks.