Today, my seven-22 mod quit on me. Blank screen, but sometimes it would fire randomly. I took it back to the shop I bought it at and the guy through it away and gave me a brand new one. Not within one day I am encountering the same problem. This is a screw adjustable version. Im beginning to think "made in china" is "made in china," anyone have a solution to this problem? And yes battery polarity is correct I also vape mechanicals..