No sound from Speakers but the audio system is on. Volume control doesn’t work

I have the mark levinson audio system and when my sound stopped working it was because water leaked in from the top of the trunk (rubber wasn't seating well, applied a adhesive) and got on the amp. It is located in the trunk, passenger side, had to remove the panels and sent it to a factory repair shop in NY. Overall easy to get at.

Can this issue only be resolved if you take it into the shop or can it be easily fixed at home? I'm having a similar issue except my sound would work one day, stop working for a few days, and then start working again. Is this an electrical issue? If so, where should I look first? I took it to the dealership when I had warranty, but I ended up having to pay half for a new audio system and "sorry, we can no longer assist with this issue." Can anyone assist me with this?

My wife had the same problem on her rc350 and she turned off the Bluetooth on her iphone13 and all worked well. You can turn on the Bluetooth after the car starts to reconnect. Issues with older Bluetooth on rc350 going against new Bluetooth format.