My HS70 headset is dead

Hello folks wondering if anyone has any ideas on how to help me.

my hs70 headset is nearly one year old got it for my birthday last year and was going great until last night when I got an unexpected low battery warning,

so I plugged it into a phone charger overnight incase the usual plugging it into the pc had been doing a poor job of charging it. Fired everything up this morning and opened the iCUE software and it was only showing 84% charged so I went looking on the forums to see if there were others having the same issue,

after about 20 minutes or so it was now showing 70% charged.

I found a thread that suggested holding down the mute button for 15 seconds but this seemed to do nothing except show the headset as not connecting now.

checking the firmware it was up to date but I decided to do a forced update anyway which failed and I now have a yellow triangle telling me this,

Make sure your HS70 headset is powered off.

Hold down the Mute button on the headset for about 15 to 20 seconds.

Hold down the Power button until the headset turns on.

Test your headset and see if the issue is resolved.

followed this advice on the help page .....

and now I have nothing, no lights no bloops when it turns on nothing just a dead headset, I have left it on charge in the hope that the battery has discharged and will try it a little later.

Any help or advice on how to bring it back to life would be appreciated :)

thanks in advance, James