Autozone installed my battery backwards is my car screwed?

I drive an 03 Toyota 4Runner. The guy at autozone literally told me he installed it backwards. Had me start the car multiple times it was setting off the horn and all my dash lights and then when it was put in the right way I couldn’t put the car in reverse. They all came out to look at it and said they melted a fuse and then they tried pulling it out with pliers and couldn’t get it. They sent us across the street to a mechanic of theirs and when I tried to drive the car the gas pedal didn’t work. They’re saying it’s just the fuse and the harness that’s broken and trying to claim the wiring on the harness was “already corroded” but I just had this car fully inspected and entirely repaired by my mechanic 2 days prior to getting the battery. For the record the battery was fine and having no issues my mechanic just said they tested it and it was at 50% so I’d likely need one soon so I figured I’d get it done just to not deal with it later. Even if they fix the fuse could this have done any long term damage to my vehicle ?