This happened to me a couple of years ago with my Varicam 3700. It turned out to be a blown fuse in the camera. The good news is that Panasonic fixed it for free because of their 5 year warranty on the camera.
Having said that I did have to take to a Panasonic service center to be fixed. They did it while I waited. I asked if I could repair it myself and the service tech told me “only if I was really good with a solder gun.” (which I am not) The fuse is the size of a very tiny watch battery.
I have not had any trouble since then but I was also told to make sure the camera is turned off before plugging anything into a d-tap or 4-pin power connection.