The Big Joe I am working on when first started looking at it would not move and the battery would sometimes read 0% and sometimes read 100% and alarm code 6.4 was on the display. The more I worked on the jack it would only display NO BMS NO CAN CTR. I check the wires #30 and #31 and had no continuity in one of the wires. I replaced the wire harness 1125-520001-30 and fixed the problem. The wires I checked are red and yellow wires that are twisted together. The wiring harness that is in the handle does have a resistor in it and it reads 120 ohms. To check the harness I disconnected the main controller, battery, and accelerator. I did look at the old harness and the yellow wire is broken where the handle pivots about 6" from where it plugs in to the handle harness.

We had same thing happen to ours, Just had our bourd replaced a month ago, did you ever figure anything out?
Thanks