DavidS.

How about that? https://www.ebay.co.uk/itm/3-7V-2000mAh-Lipo-polymer-Battery-103450-JST-1-0-1-25-1-5-2-0-2-54-connector/123706242868?var=424301887760

I did exactly same thing like you , soldered the board from original battery to the new one but the headset did not turn on. So I removed the board and connected a new battery without it like before, but something went wrong I think because headset is not working any more. Aghrrrrrr , I should leave it without the bord like at the first time, I couldn't get a green light even after 10 hours of charging ,but headset was working for me for about 5 days without charging ( about 3-4 hours of use everyday). I also check all the wires and they look OK. So really do not know what went wrong. I think it's a time for a new headset, this time I will look for one with battery that can be replaced easy. I am so f..... ? OK, so I just find out that the battery was flat ? after charging I soldered the board back to it , put it inside the headset and it is working fine. Uffffff , I am so happy ?