Follow up to both questions below on 2002 Cadillac DeVille

After 3 days W/O radio and any warning chimes, (all audio related devices) started the day with a totaly dead car. No power for ANYTHING! Next step, put a meter on the main Batt cable, and await a hook to drag the vehicle out of the driveway.

Asked by for the 2002 Cadillac DeVille