A device error is caused by an input being active while the system is attempting to learn the limits. Check the lights along the bottom row of the control board from terminals 16-41 to identify the active input.
The only light that should be active is 35-stop. If no other light is lit, try learning the gate once more while watching these input lights and pay attention as they may only flash for a split second. Once the active input terminal is identified, investigate the accessory connected to this terminal (refer to the instruction manual of the accessory for troubleshooting steps).
If no active input light was identified and the system has Nice BlueBus photo eyes installed, check their alignment as they can also cause a device error. When optimally aligned with one another both sensor's status lights should give a steady pulse about once per second.
If no active input was found, resetting the control board could potentially clear the device error. To do this disconnect power from the control board and hold down on the Up, Down, and OK buttons all at the same and reconnect power. Once the screen comes back on, let off the buttons then press functions and scroll down to 10-Default then press OK five times. The board will now be in a factory defaulted state and the learn cycle can once again be attempted.