Yeah, I would be curious as to some of the variables at play here. I will say, I've bought most of mine from various retailers, so they were not coming from one source each time. I don't think counterfeit Tubes would be common but from what I understand they do exist, at least at one time they did. I had an older MT series (?) Nitecore many years back, one of the 2x AA lights they used to make with similar results - it was dead in about 5 weeks. Never dropped it either. Not really sure what happened. My oldest and longest lasting Tube actually just died the other day. Looking back at my order history it was over 3 years old. However that wasn't the norm, others I bought were dead within weeks to less than a year, so it varied quite a bit. Although I didn't totally write Nitecore off, I bought a TUP this past Christmas and it's been working fine. However any premature problems will likely make it my last NC.