Arduino Mega and Adafruit motor shield trouble

I am having trouble getting 4 dc motors to operate on my adafruit motor shield. Yesterday it was working fine. Once the robot turns on the motors instantly activate, but all that change when I uploaded some code to navigate my robot. Now when the robot comes on the motors do not operate. I took the code off the Arduino that the motor shield is connected to and the motors still will not operate. I tested the motors individually and found that they still work, I did not change the wiring because that wasn't the problem, I tested the Arduino and found that that still works, so I am left with the assumption that something is wrong with the adafruit motor shield. When power is supplied the adafruit lights up, and I tested its functionality with the ping code for ping sensors. Just like with the arduino it works. Now I am confused as to why my motors will not operate through the motor shield. The motor shield is powering on, but it isn't powering the motor, possibly because it isn't getting enough. The problem with this theory is that the batteries I am using are new, and the wiring from the controller to the shield hasn't changed when it was working. Can come please help me understand what potential issues I could be facing?