If you have a comm error with the display, you’d better try running the motor with the display unplugged. Too bad you don’t have any other comm options (bluetooth or RS232), because the controller may need to be set in the program. There has to be a switching circuit, a wire that powers the controller. It can be going to the throttle if it has a switch, or going to the display if the switch is there. You just need to switch this wire to the + battery current.
The phases are the 3 big wires going to the motor. They are not always color match, neither the halls. Blue may have to plug on the green, etc... it is common that we have to find the proper combination to match a controller with the motor.
First things to test are: the 5v circuit of the controller (acc, ebrake, throttle, halls red...), the halls circuit alternate signal when the motor rotates. If the controller does supply current on the halls and phases when throttle is applied, then it is only a matter of finding the proper color match combo for halls and phases.