There is no upgrade command in the CLI.
Considering that amidi is enough, although you’ll need to enter the device in upgrade mode manually, I wasn’t planning to add this feature.
Still, it would be quite easy to implement The command would take the form connector-upgrade.
For now, take a look at GNU/Linux: Best method for OS update - #13 by aMunchkinElfGraduate on upgrading over GNU/Linux.
Edit: I actually implemented this. 