If all dead and battery good - try fusible link - it's not quite what you think it is, looks different;
Sparky's Answers - 1994 Chevrolet C3500, Replacing A Damaged Fusible Link
For the record - just TWO DAYS ago, I got to replace a dead nuts shorted battery in my daily driver 1999. Cranked a little slow one day, next day nothing and would NOT take a charge. New battery, now zero issue.
angela