93 c1500 no crank no start doesnt hold a charge

I am currently dealing with a unfixable problem with my 93 c1500 5.7. It was entirely rebuilt. Motor, trans, everything drivetrain is new or rebuilt. Nothing on the motor was reused. New fuel pump, new fuel screen, new fuel filter. All new sensors and new grounds except battery terminal wires cause they still appear good. I've recently been trying to solve this no crank no start. Battery is new, alternator is new, not a refurbished one. My battery charger indicates the battery is full of charge, yet it wont start. In fact the truck acts like it has little to no power at all. Interior lights are dim, dash lights come on, but that's all. The truck will start with help of the battery jump box. She'll start up and just chug along as if nothing happened at all. I have been through 3 new batteries since this issue started. I have had my alternator tested. I have checked every single fuse in the truck. Nothing was blown. Has anyone experienced this with these trucks ??

I am currently dealing with a unfixable problem with my 93 c1500 5.7. It was entirely rebuilt. Motor, trans, everything drivetrain is new or rebuilt. Nothing on the motor was reused. New fuel pump, new fuel screen, new fuel filter. All new sensors and new grounds except battery terminal wires cause they still appear good. I've recently been trying to solve this no crank no start. Battery is new, alternator is new, not a refurbished one. My battery charger indicates the battery is full of charge, yet it wont start. In fact the truck acts like it has little to no power at all. Interior lights are dim, dash lights come on, but that's all. The truck will start with help of the battery jump box. She'll start up and just chug along as if nothing happened at all. I have been through 3 new batteries since this issue started. I have had my alternator tested. I have checked every single fuse in the truck. Nothing was blown. Has anyone experienced this with these trucks ??
If you think it's unfixable, it probably is. New attitude is needed.

Fix the issue with the battery power to the electrical power distribution for the body, and/or no power from battery to cables (hard, black lead-oxide non-conductive corrosion is the usual cause.) The battery terminals AND the cable end need to be BRIGHT SILVER-color; or BRIGHT BRASS color depending on what they're made of.

BIG battery positive cable goes directly to the starter. There may or may not be a problem with that cable.

SMALL positive wire goes to power distribution block which supplies the passenger compartment and other accessories. On my truck (1988) this is under a plastic cover on the firewall, right side. The service manual you should have will tell you where the power distribution is on your truck. It could be that the wire for the distribution block does not go directly from battery to block, it might be a smaller wire from the starter solenoid to the block.

I pulled every wire off the studs of the distribution block and cleaned the wire ends and the nuts. Many of them had minor corrosion although none of them were really horrible.

"Won't hold a charge" is an entirely different problem. You may have a parasitic drain that discharges the battery, or the battery could be faulty. I'd expect that if several batteries have this problem, it's not a problem with the battery. You'll need to test for parasitic drain INCLUDING conductive slime on the battery that needs to be cleaned-off.