I'm not technology department, My idea, If I find the motor kits do not work in Golden, I do something.
First of all, I am using a multimeter to check the battery voltage, LED lights lit up on the thumb- throttle ,that should means the battery with voltage. Once again I pull brake handle "1" and "4", try to test again, and if not, I'll change your thumb "3", perhaps thumb is broken, if not, change a set of signal lines, finally still is no good, may be a motor is broken, the most likely is the problem of controller.
This is just my observation from the surface phenomenon, is not essential .
Hope everthing is ok.