I've finished both sides of my ergo (left side has the mini usb) and the left hand works perfectly fine when the trrs cable is not connected to the right half. As soon as I plug in the right half though, the whole keyboard stops working. did I miss something? Everything looks good to me, so I can't figure it out.
I forgot to mention, I'm getting 2.5v on both sides of the TRRS connector, my I/O Expander has the little notch facing toward the TRRS connecto, and all of my diodes have the black line for the cathode facing the square pads. I don't see anything that can be wrong.