Thanks, @agners but I’m struggling a bit to follow your instructions. Basically when I attempt to connect to the HA Yellow via USB from my Mac, I just get a blank screen. (FWIW, I’m using the built-in screen command in Mac OS, and the screen /dev/… command yields an error that $TERM is too long… sorry. So I ran export TERM=“vt100” first.) I’m simply seeing a solid green LED.
FWIW, my image is installed on the NVMe (my CM5 does not have embedded flash storage), so I could presumably pull it out of the HA yellow and mount it on my Mac using a USB adapter. But then (a) I’d have no idea what I’m looking for and (b) I’d have no idea how to fix whatever is wrong. (There is a LOT on that NVMe – including system backups --, so I would NOT want to just overwrite it with a new image 
)
Thanks!