Thanks for the advise. I, too, have been having problems with the headlights flickering and clicking when the brights are on, and the radio losing power. The ground wire was loose, however, it was the chassis end of the one running from the battery to the chassis. You can see the brown wire in the picture above, bottom center. A 10 mm wrench, and no more problem.
I mentioned it to my local dealer, who suggested that the problem may be originating when the battery is hooked up after being disconnected for shipping.