bad grounds will create many a ghost to chase in the electrical system. Clean battery to chassis , coat with some dielectric grease. Check body to chassis ground straps (cooper ones off the fire wall) When I say check ,I'm talking removing-cleaning contact areas-grease. Make sure starter is grounded. Theses are freebie fixes--square that away, and move on to other areas if need be.
When you say dead ,engine not turning over ? Or not firing?
Well Bullitt, you know how it sometimes is here...