Engine Rattling sound on 2016 Toyota Prius

We were installing fog lights for my car, they ran the power wire to the negative, then positive and then the fuse box underneath the steering wheel for the 15amps, then a problem occurred, before I describe the problem, I told this story to my 20yrs experiences friend in cars and he said, he shouldn’t have put the power line or ground line to the 15amps inside the fuse box, instead it should of been the positive battery or 30amps headlight, because that 15amp fuse is the radio amp which creates a sound inside the speakers by alternator transferring the sound into the speakers, my question is, I don’t think the stereo is the problem because my friend said you might need a new stereo, but the sound comes underneath my feet, the engine got louder, the battery got louder, the car sounds very weird like a hissing sound, static sound, like sparks and you know those old Vokswagen engines that have that weird rattling sound to it, that’s how the engine sounds! Please help.