Disconnect the USB cable and connect all the batteries.
Check that the LED of Bluetooth module is blinking fast without pairing
Open up the App, you will see the a red flashing circle on the left. This means the bluetooth is not paired.
Click on the Settings Icon and Select "Connect to Car". Select the HC-05 bluetooth device and enter password 1234.
Once the circle turns green, then the phone is connected. Use the Up, Down, Left, Right and Speed buttons to test your car.