Parking lights stay on?

I have a 2018 Thor Majestic RV. It is built on a Ford E450 chassis. Parking lights started blowing fuse 22. Had a backyard mechanic look and he said he found a burned through wire touching the exhaust and he fixed it. I don't know what else he touched but when fuse 22 was put back, the parking lights and the yellow lights up front stay on all the time, even with the truck turned off, lights off. He said he thinks there is a relay in the fuse box that is integrated so the whole fuse box has to be replaced. I am unsure. How can fixing a shorted wire cause another problem to start? I have no wiring diagrams and can't find any online. Help!