Did you ever get the truck operational? What style of battery plugs is used? Assuming they are the "Euro" black pin plugs, you have an issue with the communication pins and or the positive or negative pins also. They wear and are not designed to move, so when they wear, the contact is lost. The 4 smaller pins are for can communication back and forth from battery and charger. Turns it on, may have a temp monitor, type of charging. Delta Q, CAN, or non can charging format. There should be a drawing for your pin locations to be in correct position. When the plug is apart, never have power and or touch any of the pins together. You may have to reset the BMS internally in the LI-ION battery only if power won't turn on the UIM display.

Pins are 98% the issue unless they broke or touched together.