ddj sx fx light just flashes

When I Connect the usb cable to laptop the fx 2 button just flashes and the device wont even be recognized by the laptop. ive re installed the driver and serato. i cant update the firmware because it says ddj sx not connected. ive tryed differant usb ports. my laptop worked well with another ddj sx and ddj sx 2 . ive also tryed to factory reset the controller. the ddj sx doesnt even show up under devices. no luck. help?