No Power!


I hoping someone can give me some help.

Over the winter I tried starting my ’99 Polaris Magnum 500, It was very cold and was struggling to turn over, I ended up draining the battery….. so I took the battery in and charged it up. a couple months later I just went and put the battery back in now that the warmer weather is here, and now I get NO POWER!! the ignition lights don’t even turn on, nothing…. even my winch is dead… the battery is showing a full 12V… but no power at all….. Before I start either ripping this apart to figure it out or lug it to the shop…. can anyone give me any hints to look at?