Wrote up the details of the spacecraft-mode debugging job.
Customer's module couldn't connect to their USB device, on the other side of the Atlantic from here. I didn't have a similar device to test with. Ended up sending them an experimental firmware that would dump the contents of memory encoded into an audio signal; they recorded it and sent me a WAV file; from that I was able to figure out what was wrong and patch the firmware to work.
https://northcoastsynthesis.com/news/remote-debugging-the-gracious-host/