I thought Nitecore lights were of better quality!
Well, that's your mistake! I made it, too...
My advice is to try to get your money back from the dealer. That's what I should have done with my POS Nitecore, rather than screwing with it trying to get it to work right, or "testing" it, like a moron.
If it's anything like the EZ123w I had, then it's a pathetic joke of a light in several respects. Seriously, it looked good on the surface, but is probably THE worst executed flashlight design I've ever seen.
After fooling with it a couple of times, I gutted it for the Q4-5B emitter, and the rest of the light went in the trash where it belonged.
You can try pulling out on the center of the spring contact. The "spring" isn't much of a spring, and can get sandwiched together from the light being screwed into the constant on high mode, or apparently from the impact of those horrendous 8" drops.
You may have to pry on it with something like a jeweler's screwdriver to separate the loops in the spring. At least that's one of several issues my EZ had out of the box, along with having a foam ring that kept it from working with ANY battery, and a head that instantly filled with water when dunked.
Pure garbage with a $50 price tag