(Note to self)
Flashing green = no wifi connection
The Core does not support 5 GHz and channels 12 and 13.
Hold MODE and shortly hit RESET, keep holding MODE until led blinks yellow.
In DFU mode the firmware can be altered using the USB port and Particle CLI.
Hold MODE and shortly hit RESET, keep holding MODE through yellow till it blinks white.
Hold MODE for 3 seconds till the led blinks blue.
On CLI run
particle serial wifi
The ‘doctor’ program will wipe the device clean, then install special diagnostics firmware to run a bunch of tests and finally it will guide you through the setup process as if the device is brand new, but with the lastest firmware.