Insert pin into pin-hole located below the speaker driver and between the lower two screws, and simultaneously press the Bluetooth button. The headset will blink and chime.
Wait for 10 seconds for reset to complete — blinking stops, and you will hear a chime on the headset to indicate factory reset is complete.
If the headset is no longer connected to the dongle after a factory reset, unplug the dongle and plug it back in to restore the connection.