I had the same problem with mine. Then I realized you can unscrew a small section towards the bottom (to adjust size) and I had to make mine smaller. It wasn't making proper contact.
Also the button screw is adjustable, I also had to make mine taller so it would make proper contact with the battery.
Yeah thats not the problem anyone have problems with efest battery tops this new nemesis has the same top and bottom contact. Its like the big screw contact on my bottom on the old one, but the old one has a small pin contact. Stupid friend fried the old one but brand new one won't fire I suspect top contact ahhhhhggggrrrr!!!!!! Need my vape!!!!