Thanks for the great stories on debugging Particle Photon. I am halfway through following the steps you outlined. I am adapting them for use with the RedBear Labs Duo, a Photon-like device.
I have a question about the make command. On the original story, you specified MODULAR=N, but you do not use the same here. Also, I can find no mention of this argument in the Particle firmware build page. It is needed or not? How difficult is the debugging if it is not used?