03 Expedition will not start
 

My Exp will not start. it has power and everything comes on however I have a buzzing noise coming from the passenger side when ever i turn the key on. If I try to start nothing happens. The dealer is trying to tell me that I have water entrusion possibly from a leak from my windshield. It has not rained in over a month and i have not washed my truck and I have never seen any water there. They are telling me that I need the Junction box (fuse box)replaced. I was under the understanding that if water touches electricity then i should get a short but they are saying that it has corroded over time. they also said that this is a know problem with Exp. and F-150's. Has anyone heard of this?