If there is no audio outputting from the Kilburn II, then it is likely the wrong audio source is selected.
Ensure that the audio source is connected to the Kilburn II either by Bluetooth or 3.5 mm input. Check that there is no other device connected that is playing.
Alternatively, the volume could be set too low on either the audio source or the speaker itself.
Slightly increase the volume on the audio source or your speaker.