The Odroid images are based on this repo, check the readme there how to build your images
--resinio flag is required to build “managed” images with the supervisor in them, that can connect to the dashboard.
When the image is done, on the install media you have to add your own
config.json (that you can download from the dashboard in the advanced settings of the
Add a device menu, or can generate from the CLI).
That is the same for the beta images as well, just download one from https://dashboard.resinstaging.io, replace the
config.json with a production one, and user that to provision a device.