You disconnected while under power didnt you? if so the controller output transistor(s) have failed. most likely the cause why it doesn't work anyway.

If the motor was working before you unplugged it then check that you have plugged the connectors back in correctly. Sometimes a pin can back out of a connector when re-connecting.

At this point you can use the meter to check the brake safety cut-out switches for correct operation. Also, you can check the throttle control for the correct signal it should send to the ECU. These tests won't help if the display lights aren't on, but if they are, here is where you can do it. A wiring diagram can be quite helpful at this stage of the testing. Make sure to power off the bike and disconnect the wires at the ECU during these tests.