I've been using the headphones for less than a week. They worked perfectly until today when I noticed that when I turned them on, the voice guidance that says "Power on" or "Bluetooth paired" wasn't working. You can't hear anything, it's practically gone. Also the max volume is much, much lower than before and when I use the "+" button on the headset to raise the volume, it actually turns the volume to minimum, pressing "-" does the same thing.  Skipping a song by holding "+" or "-" works.

I tried both resetting and restoring to factory default, but the result was the same.

Please advise.

Thank you!