Bummers you've had problems with yours. So far mine's been a little trooper and I absolutely love it. The buttons are easy to press, the menu is instant access, battery level indicator works great (button), and it's so light weight it easily makes it into my goto list.
I use AW-IMR 18650's from RTDVapors, the flattish topped ones, because not only are those legitimate, but they perform great. I go through 2 batteries a day (actually, 1 & 1/2) with it kept at 4.3v with a 3.0 carto/tank.