From my best experience, pls check : when you replace airhole pin pls be very very VERY careful there is a very small and thin insulator on the upper part (the insulator like ring is to keep airhole pin became positive) I think you are miss that thing so it shorted.I installed the smaller pin and I am getting a message that it shorted on one mod and when I screw the atty onto a different mod, the message is that the atomizer is low. I did not lose the positive post insulator this time, but it won't vape. I've got to have done something wrong, but I can't figure out what it might be. I'm off to watch some videos you guys posted for me the last time I screwed this up.