Help - my Infinity TSS-SUB500 is making a weird noise and the standby light is flickering.

Noise is as if it is being played and outputted through the subwoofer even when it isn’t even plugged into my receiver. Keeps making the noise when I play audio and it sounds very distorted. The speaker is designed to turn on from standby automatically when an audio signal is present. Sometimes it works fine but 100% of the time about less than a minute after no music is being played, it goes into standby mode which is when the light begins to flicker and the subwoofer will make an odd sound. Sometimes it makes the odd sound even when playing music which makes any bass sound very distorted and the standby light continues to flicker between red(standby) and green(on).

I posted a video of the sound it makes on Reddit (they redirected me here):
 
Drewy,

When the red/standby light illuminates, the amp is turned "off", rapid on/off cycling could cause distortion.
The Auto Mute/Turn off should not occur time until 5 to 10 minutes after signal is removed, which would indicate something is wrong with that circuit, or the volume control or LPF circuit feeding it.

If you are familiar with repairing circuits, the service manual will help:

https://www.manualslib.com/manual/1699071/Infinity-Tss-Sub500.html?page=27#manual
If not, you'll probably need to find someone who is to repair the problem.