DDJ-SX Only Connects after Firmware Update

DDJ-SX won't connect to serato. Pops up for a split second then says no hardware. On the unit the 1 & 2 channels lights are fully lit. The DDJ-SX will only connect and function if I put it into firmware update mode. Update the firmware from my retina macbook pro and it restarts and connects as it should to serato and works perfectly. If I unplug the usb cable and plug back in, it's square one all over again with no connection and the full meter lights for 1 & 2. How do I fix this?