I have BrickPi connected to a Raspberry PI 3. The hardware test sometimes works and powers the motors, and other times it doesn’t. The script runs, it says its sending commands, but the motors don’t move.
Interestingly, sometimes powering down for a while and starting back up later, running the same exact script, works and the motors run.
I’ve booted up both with and without any sensors plugged in and it’s still unresponsive when it doesn’t work.