It could be a short if negative is switched. Short positive to the switch and ya gotta blown fuse. Short positive after the switch ya gotta blown fuse when the switch is turned on and dark when the switch is turned off.
JOB ONE
Take switch loose and see how many wires connect to the terminals on the back and report back.
"Take it back to the dealer for warranty" sometimes costs fifty dollars in fuel and blows a whole day. You and a hundred others line up for Saturday warranty work. If not on salary, missing a day of work can get a little pricey. Especially if the boss has scales and 3 inch incisors.