+1 Fuses blow if there's a fault, which could be caused from a number of things. If you don't know exactly what happened, nor know how to properly test things to find the problem as well as fix it, you should never just replace the fuse and turn the amp back on. You risk further damage to it. This is just part of ownership of any piece of equipment. If you live in the US, you're much better off than those who'd have to ship their amp from another country for repair.