My book 3.0 does not have USB interface

I purchased 2 My Books 3.0 for work. One of them I could not connect to USB cable. I dissembled that box to check the USB interface. There are only the on/off switch and power supply on that board, but no USB interface. My coworker thinks WD did not do the final test. Do I miss something here ?
Please help.

Are you able to post a picture of that hard drive, (Front and back) including the label with the model number while hiding the serial number? Some WD My Book units do not in fact come with a USB port because they use other type of connectors. The My Book Thunderbolt and My Book Live are examples of this.