@Zax I have, yes! All of the set screws are completely secured (just double checked to be safe). All of the belts are tightened, the carriages don't wobble when shook, the controller is properly connected, the COM port is set to 115200 baud, the laser is properly focused, I've booted the default firmware onto the controller and been using T2Laser, laser mode is enabled and the potentiometers are giving the maximum current that they can, so the motors are extra torquey.
I have absolutely no idea what the issue could be at this point, but I'm open to further suggestions.
Thanks for the help so far!