Belt drive to change (RSX850)

I am new to the forum and glad to see it exist!

I suspect that on my last ride I blew up my belt drive. It made the same sound as with my sled when it does happen and my RSX went neutral.

Now on my sled I can quickly replace it and easy to locate. Any one could help me with my three questions ?
1- My machine has less than 1,000 miles. Ain't that early to happen?
2- I get conflicting info about its location. Below the driver seat or under the dumping cargo in the back.
3- Is it easy to replace ?

Thanks!
Wawaron