Motor works but lights/horn/dash Don't
This failure state is uncommon but is something you could look for if having problems.
The red and black power wires going to the controller has a small red wire soldered to the ring terminal as seen below (The black has the same little wire so check the black too). This goes to the 12VDC voltage converter. If this becomes de-soldered or breaks off it will prevent the lights, US, horn and dashboard light up but also could make the motor run slow.
You will need to pull out the controller you can use this video to help you out removing the controller. Just make sure you removed the battery before proceeding with this
Once you have the controller pulled out this is what you need to look for: