If the Bluetooth connection is established, but there is still no sound output, check if the volume is turned up on both the phone and the helmet. Adjust the volume on both devices to ensure that the sound is not muted or too low.

Another possible reason for the lack of sound output could be a faulty connection. Check the Bluetooth connection between the phone and the helmet. If the connection is weak or unstable, try resetting the Bluetooth connection and reconnecting the devices.

*For Android phones, enter Bluetooth settings - Helmet headset, and tap to enter it and set the audio output.

If none of the above solutions work, there may be a problem with the helmet's audio system. In this case, contact the manufacturer or customer support for further assistance. They may be able to provide troubleshooting tips or offer a repair or replacement for the helmet.

In conclusion, if you are experiencing issues with the sound output on your helmet while playing music from your phone, first check the Bluetooth connection, adjust the volume, and reset the connection if necessary. If the problem persists, contact the manufacturer or customer support for further assistance.