Boss Radio Blowing Fuses

I'm trying to put the boss in my icehouse I'm using the negative post on the battery for the ground. but that wire is about a 4 foot stretch to the battery. The 15 amp fuse blew when I hooked up the main positive wire. I also wired the ign switch lead direct to the positive post. Every time I touch the positive wire to the post it spark and the fuse would blow again. as I grab another fuse it turn out to be a 20A and the spark led to not blowing the fuse but instead started to smoke at the inline fuse just behind the radio. Now I cannot get and power at all. How does the 3 circuit protection work or did I blow it up for good.