Did you check out the factory manual link I gave you?. The part you are calling the distribution box is the horn relay that I described as being on the engine side of the radiator support, drivers side next to the radiator. The wire you are showing disconnected is for the key warning buzzer, not needed if you don't want it. The junction block I was talking about as I said is mounted on the headlight side of the radiator support on the passenger side near the battery. If as you said there is only wire from the battery to the horn relay then someone eliminated it. Its not necessary except if you need to change out the battery cable unless it's just connected on an aftermarket clamp on battery cable end, and then not needed at all. The wire you describe as shorting out on the washer tank mounting bracket is the main power feed I was talking about and was likely your problem. As far as the wiring and the quality of the electrical work done to that poor car before you got it all I can say is wow but unfortunately I've seen it many times with home mechanics that know just enough to be dangerous. All of those non soldered crimp on connectors and worse yet house wiring twist connectors are all an entry point for moisture and carbon build up. They will work but I call them ticking time bombs just waiting to relegate you to the side of the road. Hopefully you are all set for now until you have time to either go through that harness asses and repair if feasible or just replace as you said.