Brake issue

I am new to ATVs I recently bought 2 polaris sportsmans. the most recent purchase is a 2014 570 EPS with 71 miles. The guy I bought it from stated that he had the 100 mile service done, I but 70 miles on in last weekend and the the brakes started getting soft ( hand brake) and now are not working much. With this model the brake needs to be squeezed to start the machine… so I am also having trouble starting the machine…

Any suggestions????

thanks for any help

Nancy