This is a pretty broad issue and could be caused by any number of things. I will attempt to go over as many common possibilities here that you can work through to make sure the device is working correctly. To minimize variables, it is recommended that you use a wired connection directly into the chair to test this out.
To make testing as easy as possible I suggest you connect the chair to your phone or some device capable of playing music and play some music.
- Check the chair is powered on. When powered on there should be a blue ring around the volume knob.
- Make sure the volume isn't turned down all the way.
- Make sure the red and white cables are connected to the proper port. When using the wired connection you need to connect the cables to the first set of red and white connections. The connections on the left (top and bottom) are used to input audio and the 2 on the right are for audio output.
- Make sure the audio cable is not damaged or broken. These kinds of audio cables break very easily. Even if you never move the cable it seems as though gravity is enough to make them break. Make sure there isn't any damage to the cable. Wiggle it around to make sure that there isn't a bad connection. Even expensive cables break quite easily.
- Inspect the audio cable for any visible damage.
- Inspect the audio connection on the chair to make sure there is no damage to it.
- Make sure the audio source is outputting audio.
If anyone has any additional troubleshooting steps, please add them to the comments section below and I will add them to the list.