Just for the heck of it, change the radio fuse that is inside the car (bottom one right in the middle) just in case. I also wonder if something is shorting out somewhere.....if all the fuses are good then I would move on to looking for any sort of short. Also could be a poor ground somewhere.

I have burnt out my radio fuse 30-40 times I do not believe there are any other fuses on that track anywhere else, GM did one thing right this time