When dealing with a dead short, I will replace the fuse with a test light. Just insert straight pins into each of the fuse "sockets" and connect a test light with alligator clips to pins. Since you are shorted to ground, the light will be on. Then start to "jiggle" wires or any items on the circuit that you know of, and see what happens to light. If it flickers or goes out, you have found the cause of the short.
Dr Quick