Puck probably answered your question while I was typing, but if not here some other things to look for.
It sounds like a broken wire inside the camera itself. Even though the insulation looks good around the wire it still could have a break in the wire.
I would take the camera down, take the back cover off again and move 1 wire at a time until the camera comes on. Be sure to only move one wire at a time. That should be the wire that has the break in it. This could be the small red wire for the power or could be the small yellow wire which I believe is the video. Do you have sound coming through with no video or no sound and no video?
Also while the camera is attached to the wall try moving the main power wire around, if the camera comes on then you probably have a break in the main wire and not the camera itself.
This could be frustrating to figure out if you don't know anything about splicing or replacing electronics. This is just one item that could be wrong. There also could be something wrong with the electronics board inside the camera, maybe something loose. In any case, if your not comfortable splicing then you should just replace the camera.
Do you happen to have another camera you could switch with the same power supply? At least then you could narrow it down to the camera itself or the wire that goes to the power supply. Hope this helps.