Why is my Harley not starting? (Detailed account)

So I just bought a used 2014 fld Dyna Switchback. I had it shipped to me and when I first got it, it started, but then the second time I tried the engine made a wierd sound like it was trying but only once. And now when I flip the "on" switch before I start it the electrical system lamp and check engine lamp come one and there is a beep that sounds. And when I press the starter the engine just rattles. I thought it was the batter but the lights seem to work fine. What do you guys think?