What is causing my car not to have power? (honda civic)?

I have a honda civic ex 1994 my car hasn't been wanting to start so I thought my battery went out so I went to go buy a brand new one and still nothing now I have no power at all in my car. So I checked the fuses under the hood i seen the 80A fuse was blown so I went to go buy a new one and as soon as I connected the battery back up the new fuse had blown again. Can someone please help me out what can the problem be?

A short circuit, perhaps a diode in the alternator.