Turn the bars until fluid reservoir top is level and open the screw cap. If the level is high, suck some fluid out with a syringe and put the cap back on. Then get the fluid changed.
The bike has not many miles but is 4 years old. Brake fluid absorbs water so that could explain the problem. Also make sure the pads are not sticking in the calipers because that can overheat the brakes.ii
When its all done get out and use the bike. Its currently done something like 1300 per year. It needs some proper hard use to free up the engine which wont be properly run in until it sees 10K.