Normally you should not get an alarm when you open the main door. You will if there is an error though. Then the VFD will say "Call Attendant" and the top of the candle will blink. When you open the door the alarm will sound and the VFD will tell you what the error is. Then you turn the jackpot reset key a couple of times to clear it. You may have to press and hold the MPU self test button for 2 - 3 seconds. If that's the case it will tell you that in the VFD and when you release the button it will say please close the main door. After that the machine should be ready to play.