[Roverchef]

You are missing(corrosion) a ground somewhere. Check all chassis to motor, battery to t-box, etc. Worst case you could add a ground directly from the battery to the drivetrain and see if things start to wake up.

 

[Roverchef]

Guys - here was the issue. The starter relay failed to "close" I think. It sent all the voltage down the ground wire and burned it completely out; the entire length of the ground wire melted. After running a new ground wire from the female end of the relay and replacing the relay, it fires up and runs again. Hope this can help others if the situation presents to another member here. Thank you all.

Still sounds like you are missing a "primary"ground somewhere. For that to melt down someone held the starter tooooo long and it back fed the ground.

 

[Roverchef]

I added a new heavy duty ground from the engine block, passenger side to the inside of the wing. I did confirm all the other grounds were solid. Even after this, the wire continued to smoke upon attempting a start. I traded out relays but at that point it was too late as that ground had smoked through the plastic.

But I do agree, why would that have happened in the first place? Bad main ground somewhere, or open relay redirecting current when it shouldn't have?

And, to note, the instant I turned the key to start the truck, the smoke appeared. Check out the you tube video I had posted above. (HERE )

Sounds like you got a"-"where a"+" should be...or the other way around.

 

[Roverchef]

Strange though, I made no changes to anything prior to this happening. It was in storage for 6 months with the occasional start and run and on a battery tender.

Doesn't mean it was correct to start with. Electrolysis grows constantly. The "heavy"(main) wiring on defenders is very simple to inspect/clean/replace. Start @ the battery(s) and work your way out. Good luck!