During a workout I used the volume lowering button once and found it slowly turned the music all the way down, followed by a strange continuous beeping and wouldn't turn off to reset, I then found it would let me turn up the music shortly after but every time I'd press the volume decrease it would do the same thing.
I then found even with my finger held down on the on/off I still couldn't turn the earphones off, and I thought maybe it's a battery issue but on one occasion of pressing this button the voice said I had 30% charge left.
Took them home and put them on charge for an 40 minutes, I then couldn't turn them off at all or disconnect from my phone's bluetooth, thought I'd try the app and saw there was an update to do so gave that a go.
I've just tried again and still no response through the buttons, now the volume and play/pause buttons don't work either and I still can't turn them off, strangely I can listen to music through them still though. I don't know what's happened to them but they're barely 9 months old?