No Sound / SOS Error Still Stuck After Troubleshooting / Optic Loop

The first description with loud hissing and popping sounds usually means the amp has gone bad.
And water on the amp is the most common problem.
If any module on the Most Loop breaks they all look bad.
Could be water has attacked the other modules to .
If you put a most jumper in the amp location and the SOS light goes
out it would isolate the problem to the amp or could mean more modules
are bad.
The obvious thing is to verify the amp first.
I would stop looking elsewhere till I could verify the amp.

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The SOS is out without having the jumper involved at all. There is however the "no warning tones" message on the nav screen (which is how this whole thing started...and then at some point the SOS message came and went). Does the "no warning tones" indicate the same thing as the SOS light in terms of troubleshooting? I've watched most every YT video and read tons and tons of posts but remain puzzled as the punchline to all of the videos and posts seems to be "find out where you lose the red light from the optics, plug in the jumper, and things will work / you know what module to replace. Since all of my red lights are working, this hasn't been a huge help for diagnosing what is wrong. Sounds like you are saying I can still get the red light (optical) past the amp even if it is bad? Amp needs to come out either way as a closer inspection will likely reveal there is damage as you predicted. Just trying to understand why I get the red optical light everywhere in the circuit if the amp is bad.

Very helpful, thank you. Well, you said I should get a steady yellow LED at the amp and I did. Unfortunately it sounds like that means the amp is bad right? I was a bit confused by the Bavlogic link you sent me as the picture with the yellow LED says "Steady yellow means network working and amp is functioning ok.". This is different from above the picture where it says "steady yellow but no sound or bad sound--amp is bad". And last, the third reference in that link says "steady yellow means its getting input fiber optic signal from the head unit (CCC or CIC) and output signal travels to head....but rarely it also could be some software glitch with CCC, when you don't get sound with working amp. Try CCC reset."
Did some digging and looks like I have a CIC on my 2009 e93 not a CCC. I did the 30 second push the volume knob down and it did reboot it. Nothing changed. Still no sound of any kind, still have the "no warning tones" message, no sign of the SOS message. I disconnected the amp afterwards and tested for 12v at the connector "plug". 12 volts were there. Bad amp?

Will give this an in depth read tomorrow and dive in. Quick question in the mean time...I've read posts from other folks who had bad amps from water in the trunk like I did. I started pulling mine apart (one end is fighting me and I don't want to force it...will read up on how to get it apart)--and can see some corrosion on the non plug end where the water had accumulated in my trunk. Some folks claim to have soaked their amps in denatured alcohol, various electrical sprays, etc. and had luck with it fixing their amp. No clue if they just through a hail mary and got lucky or knew what they were doing. Any thoughts on giving this a dance given what can be viewed in the picture? Otherwise, will give the link you just sent a good read tomorrow and see what I can learn. Again--much thanks for all of your help.

Got it all the way opened up (we won't talk about the fact that I missed two screws on the other end that were holding it in place...I was tired) and sprayed it with Deoxit D5 and gently scrubbed with a soft toothbrush. Seemed to really clean up the corrosion and supposedly leaves a desirable protective layer. Put things back together and plugged it back in to the car. No amber light of any kind. No similar red light either. There is however a very faint red light that was solid. I saw the note about a faint red light deep in the amp but sounds like that should be a blinking light not solid. I'm back to getting the SOS message (and the no warning tones message too). The red optic light going to the amp is still solid like before (no change there). Almost acts like the amp isn't getting / accepting power now. I did confirm 12v at the plug harness that goes to the amp. I'm about out of runway on this one. I read the link you sent me about what to look for once you open the amp up and it's above my pay grade. Couple quick shot in the dark questions: 1. Can the two black wires that go from the plug pins that go almost all the way to the other end be easily unplugged by pulling on them? Wondering if it would be worth taking them off if so and spraying them with Deoxit? Or perhaps test for 12v there if those are power wires? 2. The white grease (heat sink thermal grease?) on the top of the rectangular components...I didn't add more when I put it back together but didn't wipe off any of the old either. Assuming this isn't the problem but throwing it out there. Welcome to other thoughts as well of course. If after this it's feeling like a dead end, sounds like I'll need to either roll the dice on eBay if I can find one or try sending it in for repair. Picture of the cleaned up unit is below.