[Hectic]

What i was asking was after it stopped firing did u try flipping the selector switch around to see if it would fire in a deferent mode.
Also whts the fps on the gun? Have u been firing it out in the cold alot?
I think the lipoy be the cause of the issue tho. The trigger contacts could be burnt up a bit causing it to not fire.
When u took out the barrel did u inspect the cront area of the gearbox for cracks?
Do you know how to remove the gearbox? Its not that hard remove the plate at the end of the grip drop out the motor remove the two screws in the top of the grip
Remove all the pins in the body the gearbox will lift right out of the reciver from there you will be able to see the trigger contacts and check for black/burning on there thatll be the easy thing to check.
Unless u have a mofset in there then the burning shouldnt be the problem.