A blown fuse most likely indicates a short to ground. Start by inspecting every single inch of wire in the harness and especially where the harness bends around metal chassis parts. You may have to remove the outer harness protective insulation for inspection in certain areas. Another method is to unplug the harness at the connectors and repeat the process of turning the key to start the engine. If you find that when you unplug a certain part of the harness and the problem goes away then the problem is downstream of the connector you unplugged and this will help narrow down the area where the problem is located. I could list all kinds of possibilities such as a shorted starter or solenoid but until you do some diagnostic work and report back with your findings it will be a wild goose chase. Good luck.
