Thanks again for the info and advice.
This is probably a bit off topic, but, for a few brief shining moments, I got to experience the joy of things working properly on my quad project.
I went through the entire calibration procedure compulsively, set up Altitude Vario and Position Hold per instructions, took off on manual control, and switched on and off the other flight modes. Both worked as they were supposed to. It was fun to watch the PFD and the vehicle as it corrected for the breeze to remain parked in midair, drifting less than a meter in any direction, even after landing and changing batteries and using the mini OP GPS (which did get 10-11 satellites).
However, after another battery change, the Revo wouldn't flicker its bootup LED sequence or arm, and telemetry quit working.
So - it's back to the bench to try to figure out what changed..................