Trying to flash firmware but getting nothing from the board…
Things to check:
- The first time we burn firmware to a new board, we need to manually put it
into boot mode by holding button 2 and momentarily pressing reset
(otherwise, although the OS sees the port, esptool will not be able to write
to it); sometimes the device goes back into that state (or is in a bootloop
that prevents upload), and requires the same hold button2/touch reset
combination to fix. - Note also that the unphone9 port will usually appear as /dev/ttyACM0 in
ubuntu; sometimes it shifts over to ACM1 or ACM2 when resetting, so if
encountering problems writing to the board try changing the port (and/or the
above).