I have the same model, but mine does behave like an on/off button, being enough to solve that problem you had (no sound because some device other is paired) Maybe it's something about a firmware upgrade? I remember there was one in 2018 that enabled an auto turn-off feature past a certain time with no use. I didn't update mine with that or any of the newer ones, so if I forget to turn them off manually they just keep consuming battery.