This is only half a response because I'm barely wrapping half a brain cell around anything right now -- but when my ergodox stops working (and un,re -plugging the USB cord doesn't fix it) it turns out to be the two halves aren't actually talking to each other.
Do you have a multimeter? You might start by checking for continuity between the sound-port solder points. That it breaks so often for so many, is why many have foregone the quick-disconnect idea and just soldered wires to both halves.
Myself, I use a phone cord but even then, one of the wires on the board is just barely there, and reflowing the solder didn't make it all that much more strain-resilient so I have duct-taped it to one side to try to reduce pressure on the keyboard/cable connection.