Why harman kardon onyx studio 2 does not respond to the button

My harman kardon onyx studio 2 one day turned off, since then bluetooth, phone, volume button does not respond. The power button works, the speaker turns on, connects to the previously paired phone. However, it is not possible to adjust the volume or connect to another device via bluetooth. Is there a chance to fix it? Warranty expired a long time ago, but it's still a well-sounding speaker.