I agree with Iamthevoice about measuring your resistance. What did you use to measure the coils? On board ohms readers on mods Vamo, Innokin, or otherwise I have found not to be nearly as accurate as an ohm/volt meter from say e-leaf or a company of that sort. I'm trying to go off memory here but I believe that the minimum ohm coil that a z-mini will fire is 1.5 and if you have tweaked the coils at all when wicking them and it has changed the ohm level or you don't have an accurate reading of the build that will definitely cause it not to fire as well. I have built coils that read .30 on my ohm meter and after wicking and firing it a few times the ohms dropped to .25 when i rechecked the build after vaping it 2 to 3 lung hits, I know that it probably sounds weird rechecking your coils after vaping them but I want to know that my builds are solid and accurate. A screw loosening or not being tightened properly can cause a major dilemma in vape performance and safety.