I would disconnect the hot 12 volt lead from the white terminal block and test again- what I suspect is that another load has been added to that circuit. 10 amps doesn't really indicate a short, it indicates something else is drawing that much current. There are a few things that come to mind- compartment lights and tank heaters (with bad thermostats) are more obvious. Trying to trace the hot lead to the refrigerator to see if anything else is on it would be worth a try- and seeing if something else is inoperative when the refrigerator fuse is pulled.
The difference between the negative cable and the frame is troubling though- the negative cable should, at some point, be bonded to the frame. Even when two problems seem unrelated, there can be a common cause.