Before they have firmware on their download page of this unit but they remove it last year I don't know why but I noticed the difference between their stock firmware and the firmware from their download page.
Anyway, have you tried to use their new tool called "Avalon Miner Upgrading Tool #Beta" it can automatically detect your unit and able to upgrade automatically the the latest version.
About sending commands, use the FMS app/tool that you can download at
https://canaan.io/service/447You can send API commands under diagnose.