Not real familiar with the Maker Shield controller, but a quick look-up indicates it is a GRBL based controller, so it is likely a USB connection. The first thing I would check is to make sure that Windows sees the device. With the CNC controller plugged in to your PC and powered up you should be able to see it listed under Device Manager (please do a google search on how to locate this for your version of Windows) If it is listed it should indicate if it is setup correctly or if the drivers need to be installed. If windows is not seeing it try a different USB cable. After ruling out the cable, you may need to contact the vendor to send you a replacement controller