Well, evidently AGM battery went open, zero volts. Applying charge voltage produced zero current even after an hour... I have had once an AGM in sportster go open and also short, intermittent open degenerated to dead short. That pulled the system below critical and machine ignition stopped. In this case simply open, as in internal "fused"... will crank on jumpers 2 1/2 years old... I still have 2 beers left...
Suggestions respecting new battery are welcome. As in sources and types... I favor AGM due to limited access...