I'm having the same problem, though it is intermittent, and I can sometimes get it to work for a while by jiggling the connection at the projector side.

While this thing should be "obsolete" by now, I figured that 720p @ 2000 lumens is still better than most of these LED mini projectors, so I just picked up one of these Dell 209x used for $25...only to find out that it also seems to suffer from this issue. If I had to guess, I would suspect that the heat it generates broke some solder points on the board that has the port. As soon as my lamp cools down, I'm gonna take it apart and investigate. Did anyone else ever find a cause or resolution?