Hi, ive bought a Audi B6 A4 2002 cab stereo, but the stereo didn't wok, seller said it was probably a fuse. I removed the stereo and sure enough rear fuse was blown. The fuse in the box looked ok, so thought good to go. Well it didn't turn on so checked back fuse, O.K., decided to change nox fuse, it fizzled and fuse blown, tried again. So it is fizzling as i insert the fuse, any ideas?