follow you positive cable until you find it
battery suspect or bad connections or cables to the battery or starter
have a load test done on the battery
You have a faulty switch, or it has corrosion in it, moving the switch through it's full travel rapidly for a while to clean the inner contacts may cure the problem, or try disconnecting the switch.
See: https://www.youtube.com/watch?v=aDN5dylOFBw and http://xplorer-manual.blogspot.com/2014/11/download-polaris-xplorer-300-repair.html
if it has a oil light on and the oil reservoir is empty , the it would be reasonable assumption that unless there is oil available to mix with the fuel , it will not be allowed to start
It is a 2 stroke that has a metered amount of oil that varies according to engine rpms and is not a pre-mix situation that you have assumed it to be
so fill the oil tank with the correct 2 stroke oil, remove the oil mix fuel and save it for a whipper snipper or other small engine , fill the tank with the correct fuel and it will most likely start
It seems that the clutch is not disengaging may need a adjustment unless it is hydro drive then I am stumped.