Does it blow the fuse soon as you turn on the key or after you ride it a while, does it blow when you do something like step on the brakes or turn the headlights on, how about when the fan kicks on when the engine is warm?
After seeing how they ran the wiring harness on my 2010 RZR-S I would suspect their is a factory defect some place, look at your harness some places on my harness they had it stretched like a E string on a violin and other places it was sagging so much it was touching the exhaust system.
Since I have seen 4 others in the showroom that the drivers side brake light wires were touching the exhaust system it wont take long for them to melt and short.
Be very careful inspecting your harness that you dont poke a eye out on the zip ties they never cut the tails off of, on the ones they did cut off they are not cut off flush so are like a razor blade if you brush up against one by accident.
As your checking the harness sooner or later you will run into the brake light switch, pull the plug off and coat the terminals and the whole plug with grease so it cant corrode, the type of connection they used here was not made for outdoors.
Start at one end of the RZR and work to the other inspect the whole thing, you will find places where their are abrasion issues, places where the harness is not supported so the weight of the harness is pulling on electrical connection with ever bump you hit, places where its stretched tight and restrained with zip ties, my whole harness was a mess it looks like it was installed by a high school kid with no skills or a skillbilly.
Good luck hopefully it just something simple.