The 500 series frame is a little different. The controller is located in the bottom of the down tube.
To access it: Please make sure the proper sized screwdriver is used. Too small or too big, you may strip the head of the screw.
Please share pictures of all connections and wires. This will help us determine if what the issue might be faster.
- Please remove your battery from the bike.
- Remove the screws holding the lower battery compartment panel. of There are 4 screws to remove from the very bottom.
- Remove 4 screws from the very bottom of the bike.
Now that you have accessed both sides, you can carefully pull the wires out of this location.
You can inspect many if not all of the connections here. To be thorough, I recommend disconnecting each one. Once completely disconnected. You can slide the controller up and out of the battery compartment.
Please share pictures of all connections and wires. This will help us determine what the issue might be faster.