I know this is an old topic but you really saved my sanity. A coin had rolled down into the vent on my 2019 sierra and a few days later I could hear it rolling around I thought. Probably did everything you did trying to find it, with no success. Frustrated and ready to tear the dash apart, I found this thread... Discovered on my truck exactly what you found. A screw in the upper console that came loose and was rolling around... Thanks for posting the topic and solution for the rest of us, you are a hero....
