All these error codes were due to the damage of the main controller (controller itself and some wires), which just above the real wheel. have to fix the broken wires and repair the main controller $300 cost.
'AC' - semiconductor switch abnormality
'AD-2' 'AD-4' - traveling AC driver to main controller communication abnormality
'AD-6' - material handling AC driver to main controller communication abnormality.
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