Same issue here. I allowed the headset to completely drain, from that point it appears to no longer charge or be able to be reset.
when plugged into a power source, the headset flashes red/white/red constantly. Take it off a power source and it dies. I have tried multiple charging cables that I know work and plugged them (with the Beats x plugged in the other end) into a variety of charging sources (1.v/2v/3v plugs).
I can only surmise the things are dead. On how infrequent I used them in the past 18 months, I would say it would be cheaper to buy some £19.95 Chinese specials than these £129.99 American (made in China) junk!