What could be the issue besides the Super Drive?

[SAWYER]

I have a late 2009 Mini I bought used, the drive has never worked or showed up in system information. The guy I bought it from online sent me a replacement Sony drive that was supposed to be new and I installed it, same thing. So I am thinking it obviously is not the drive but something else. The hard drive obviously works and I think they probably used the same sata connector board right? What could possibly be the culprit?