4 blinks then 1 blink the book says low voltage that should be normal since the contactor is not pulling in to give it battery volts. (unless I'm missing something that the controller looks for before the contactor can pull in)
The battery checked good just to make sure pulled another running lift close to it and used a jumper battery cable and got the same results. things that were tried. Swapped MIB, traction controller, operator display, relay, and contactor with a known working one. Unplugged mast cables and checked drive motor for shorts.

There should be a LED on the traction controller. Check to see if it is on and what code if any it is blinking. It sounds like you have a POST problem.