My audio just stopped working one day. No door warnings, distance warnings, stereo sound, etc. My MOST data bus system doesn't run through the amplifier and the stereo allows me to adjust radio frequency but no audio. Any ideas?

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I should have introduced myself, I am an owner of the Sapphire Black 2009 BMW 750Li 107,230 miles, runs, drives. During Christmas break I installed air ride. Stereo is professional base model but when I removed the amp the most bus fiber doesn't go though the amp.