It sounds like you have a short to ground somewhere. If you have a amp meter with a high enough amp rating, hook it up between the battery terminal and battery cable. Then pull and replace one fuse at a time untill the amperage drops. When you pull a fuse and the amperage drops then you have found the problem.
If your amp meter is not rated high enough it will probably blow the ampmeter fuse. The amp meter will then show zero amps with a blown fuse.
