Check the following.
- Check that the connected device and the left and right units of the headset are powered on.
- Check that Bluetooth connection has not been cut off. If it is cut off, try reconnecting via Bluetooth.
- If the issue is not resolved, reset the headset.
Reset the headset by inserting it to the charging case and charging it.
- If the issue is not resolved after resetting, use the following steps to set headphones to factory settings.
- Remove the headset from the charging case.
- Press and hold the button on the left unit for more than 2 seconds and turn off the headset.
- Press and hold both the button on the right unit and the button on the left unit for more than 15 seconds.
The indicator (red) goes into the flashing state then the indicator (blue) flashes 4 times, and the headset is reset to the factory settings.
All pairing information is deleted. In this case, delete the pairing information for the headset on the device which has been connected, then pair the headset with the device again.