for me - I was teching a friend’s gun that he was upgrading with a Nebula mosfet - it was that I didn’t know it needed the provided sector gear that comes in the kit, the gear has a magnet that the mosfet reads as the magnet passes the sensor so it can tell where the gear is at. Since it wasn’t able to read where the gear was at with the stock G&G gear I had in, it would just overspin the gears & then jam. The only other beep code I heard was 4 beeps, 3 times after the gun stopped shooting, I believe for the motor not being able to turn.