John Deere Ride On Mower Won't Start?

I took my mower out of the garage yesterday, it wouldn't start because the battery was down so I had to boost it. I started the mower and put it on slow idle to let the battery charge. I went about my business while the battery was charging and all of a sudden I heard this loud exhaust noise like the muffler had fallen off the mower.

I rushed to the mower and shut it off. I checked the exhaust and everything was fine. The problem is now it won't start and when I am trying to start it there sounds like there is an exhaust problem. This is a new mower I bought three years ago, 30 hrs on it.

By Terry C