I was able to reset the Dynon by removing the ship's power and then letting
the device run its internal battery down.  It reset sometime during the
night.  It was on for an hour before the ships power was disconnected.  The
next morning it was off and reconnection of the ship's battery brought all
back to normal.

Thanks to all for the suggestions.  I'm on the way out the door for a week
in Philly.  I'll report on the Dynon when I get back.

Hal