OK, got 'er figured out and it is a little scary actually. Started doing the "wiggle test" on every connection. Got to wiggling the Can Bus ports on the A2 and right away the LEDs came back up and all was well. Great - I found the problem. Not great - now I have to spend the rest of my life worrying that those plugs will come undone in flight and....
For the record, my CAN bus ports were glued in and appeared to be fully plugged in on visual inspection. It wasn't until after they were wiggled that the LED came back and the system was fully operational. I suspect minor corrosion and will inspect further as this is my oldest A2 unit.
Lesson Learned - check all connections prior to all flights!!! Just because something looks to be fully plugged in doesn't mean that it is. The good news is everything worked even with a faulty connection. The other good news was that I noticed immediately that something was not right with my LED (solid yellow with a little flicker) and I grounded the machine. It was just a test flight in the yard and not a production day so that part was easy.
I really do love these things but they terrify me so. With single rotor it is about skill and simple mechanical. With these big multirotors it is about skill but, much more importantly, it is all about the holistic well being of the entire UAV. This means systems, coms, maintenance, repair, adjustments, flight logs, test flights, checklists, SOPs and due diligence. One bad connection can, and will bring these birds down. Do the work. It it ain't right don't fly!
