Tonight our Disco decided to act dead when we tried to come home. No warning at all but turn key and nothing. Lights are dim, almost dead, windows very slow to move. Installed new battery, windows and lights are better but starter is just clicking rapidly. Possible battery cable or maybe something else. Help please.

 

Your not getting enough juice, charge the battery. Brand new batteries are not fully charged when you buy them, they charge them at the factory when they make them, but then they sit on the shelf and loose power from sitting, so depending on howe long your new battery was sitting on the shelf...
Once you get it running have your alternator load tested.

 

Ditto, give that new battery a good 2 hour charge.