OK, problem resolved.
I entered brand new territory (but what’s life about if not that??) and downloaded the 1.1h source code package from the grbl github and compiled it using Rob’s config.h, with the safety door pin commented out. After I finally (after about 10 tries) did that successfully and it was loaded into the Nomad’s Uno board, I entered all the $ parameters, and the Classic+ is up and running under CM649! 