[MPaulHolmes]

My guess is that there was some sort of overcurrent event, and it hasn't been cleared.

Also, I would start at 1 with Ki, and gradually increase. In practice, I've noticed that it is typically 1/1000 or 1/100 of Kp.

If you tried Ki = 128 each time you unplugged the control board's 24v power, it could have tripped the hardware overcurrent. Then trying the other values wouldn't do anything, since I never clear the fault. It requires a cycle of power.

So, try this: turn off power to the control board, start with Kp = 941, Ki = 0, 1, 2, ... go from there. If Ki = 1 is the best, then that means I probably do need to increase the resolution of Kp and Ki after all. There is some room to do it though.

The default Kp and Ki when cycling the controller now is Kp = 1, Ki = 0, so it should show just 512 512 500 512 ... or something like that if you just cycle power to the control board, and then do "run-pi-test". "run-pi-test" outputs the error, and 512 corresponds to 75amp. So, if it keeps saying 512, the difference between 75amp (the desired feedback) and the actual feedback is 512, which means the actual feedback is 0amps. kp = 1 and ki = 0 produces a feedback of 0amp, since kp is just too small.