[Dnick]

The "crazy" lights and gauges are almost always a symptom of a weak/failing battery. If replacement batteries are not holding a charge, then you need to have the charging system checked. After that, then you can check for parasitic drain. I'm not aware of any known issues with the radio/nav causing this problem.

Agree.... First next step (now that you've put in a new battery) is to verify parasitic drain. If that's what they already did to pinpoint Radio/Nav, then you just need to figure out where that drain is happening (ignition switch or ????). You'll probably have to take it to a good auto electric shop for fastest path to solution.... otherwise you could be chasing your tail & spending time/money w/o resolution.