Hi, we have a custom T-SOM carrier board that reproduces the normal Particle LED functionality, and some of our boards have become impossible to flash. When reset, we get about 2 seconds each of magenta flashing, yellow flashing, rapid white flashing, white breathing, and then back to listening mode.
We notice that something is pulling the MODE pin to ground, even with a 3.3k pullup (there is nothing connected to the MODE pin except a button and the pullup).
Affected devices will appear when particle usb list is run, and the aforementioned LED sequence repeats, except for flashing yellow, when particle usb dfu is run. Particle USB dfu never finishes running.
Particle usb safe-mode causes the same behavior, and particle usb setup-done returns "Done", but nothing changes.
We are kind of at an impasse here as we don't want to flash any more of our boards in case we are bricking things. The MODE pin being pulled down seems important.
Additionally it is not possible to run particle usb-reset - it gets to about 2%, then sits there indefinitely.