Some users may facing problem in Osoyoo Robot Car lesson 1:
http://osoyoo.com/?p=4906

The sketch code has been successfully loaded into Arduino, but after turning on battery switch, the car does not move. The Arduino board and/or Model X driver has no LED light on(normally the LED on both board should have LED light on).

The problem should be in the wiring of DC connector.

In order to make properly installation of wiring in DC connector, please follow these steps:
1)Twist the metal head of two red wires together , then 2 black wire heads together like following:

Then use a flat screw driver to open the DC connector fasten screw in COUNTERCLOCKWISE direction as following picture:

Then use screw driver to fasten the DC connector wires in CLOCKWISE direction , after  installing wires, the DC connect will look like following:

now turn on the battery box switch. You should see Arduino board and Wifi Shield and Model X board should all have LED turned on.

If you run the sketch in lesson 1 again, the car should move.