ROS is not able to communicate with the Jetbot I2C bus that sends the pwm commands to the motor controller

I am trying to implement ROS and deep learning on the NVidia Jetbot and want to make ROS application able to communicate with the I2C bus that sends the pwm commands to the motor controller. In the code we specify i2c_bus=1.
I followed this link


Things were going good till but when I tested pwm commands on robot nothing worked.
Then I opened the https://github.com/dusty-nv/jetbot_ros/blob/master/scripts/jetbot_motors.py file on my system and I made change in parameter " motor_ID ". I tried with different combination of 1,2,3 and 4. Only motor with id 3 is working, not able to move second wheel.
I even tried directly with this library file https://github.com/adafruit/Adafruit-Motor-HAT-Python-Library/blob/master/examples/DCTest.py
Again, this is working only for motor is 3, so only one wheel is rotating, second one is not moving.
Though jetbot is perfectly fine as I have checked the movements of both wheels with basic_motion file.

Can someone please help?