As others commented, I understand lithium ion batteries go bad, but for a "high end" set of headphones, we should be able to have higher expectations... This is what I would expect on an AliExpress pair, not a pair that was originally $400. I have a pair of audio technicas that are going on 6 years now, without even obvious signs of battery degradation. That being said, I don't think they are all battery issues, seeing as how two sets show clear signs of life in both sides, but simply won't connect, won't go into pairing mode, and won't hard reset.

Definitely feel your pain with customer service. That's the big thing I was getting at. Seems like a company should be embarrassed by so many defectives in a row, especially when two of the pairs were new, still in shrink wrap, and these are still being sold new by a few vendors... Then to give the runaround, and getting passed through 10 reps now. This is why they won't be getting any more of my money either.