MayFly Pin On/Off Communication

I am using a MayFly to control pumps in a water sampler to pump water for specified timeframes. I have the battery powering the pumps and a converter to power the board.

I have my hardware system set up, and I have checked the voltages and battery and pins throughout the system, with reason to believe that my problem is not because of any wiring. The pumps should be controlled by turning on and off their corresponding pins on the control board. The problem is that whenever the pumps are plugged into the system and the Arduino control board is on, the pumps are on. The pumps do not acknowledge any instructions when I upload code that should be controlling when the pins have power, such as a ‘Delay’ command or ‘LOW.’ The Arduino board does acknowledge when I upload new code by blinking lights, but the pumps do not listen. The pumps just turn on whenever they are plugged into power and the Arduino board is on. This leads me to believe there is something pre-programmed onto the board that is causing this behavior?

I have verified that the converter to control on/off has the correct 4V power and the battery is separately providing 12V.

Thank you for any guidance.