I'VE GOT A 1990 MX6. I LEFT MY LIGHTS ON AND REPLACED THE BATTERY. I CAN'T GET ANY POWER INSIDE THE CAR. THE ONLY THING THAT WORKS ARE MY HEADLIGHTS. I THINK THAT MY 80 AMP FUSE IS BUSTED. I CAN'T TELL IT IT'S SUPPOSED TO HAVE A SOLID CONNECTION OR NOT. IT'S THE ONE UNDER THE HOOD THAT SAYS IT'S THE MAIN FUSE AND IT'S BOLTED INTO THE FUSE BOX. CAN SOMEONE PLEASE HELP ME.

I never again click on posts that don't say what the problem is on the subject line. I have to click on dozens of posts like this only to find I could not help in the first place. Had you put CHANGED BATTERY NOW NO POWER or something like that, instead of I'M LOST, I would have worked with you. If I couldn't help then I wouldn't have to waste my time on this post and others like it. No more opening posts like this.

Fair enough, you don't like to answer posts that don't name the problem. But come on, this guy has a problem and needs help. Of you can't help him, there's no need to waste everyone's time witha post like that.

Anyway,in relation to the problem, are you getting a battery warning light to suggest that the battery isn't being charged?
If not, then I guess it must be one of the fuses. But I've never heard of a problem like it before.

Using your trusty $2 test light, check for voltage at that big fuse. Then you need to see if your big fuse is passing current. If you can't test in the car with the test light, take out big fuse, use a multimeter and read ohms, or hook up test lead to battery post, other lead to big fuse, and touch the other side of big fuse to other battery post, and see if test light does light up.

listen if the main engine fuse was blown then nothing would work. U probably blew some of the accesory fuses check them.