That's strange, have you ever tried to open/dismantle the fuse box for any reason. Fuse box is a sturdy assembly, filled with some sort of insulating paste, they normally don't behave like this.
I am sure there is a problem external to fuse box, check the hot wires leading towards the radiator and condensor fans.
Try to isolate the problem, this way you will easily figure out the problematic part.
Use only rated fuse, never install an overrated one and try to get the orginal one not some Chinese knockoff.