Building circuit

The motor driver that I am experimenting is the following 2 links. At last, I am using the second one.In this process of testing circuit, I break down one nano iot and 3 motor driver! What a mess! I still dont’t know why.

Pololu DC Motor Driver 3A, 5V-28V- MC33926
A4990 Dual Motor Driver Carrier



In order not to cause too much lost, I try to made the circuit first work on 4 simple dc motor. Then I swift to 4 linear actuator and increase the power.