As DiapDealer said, the screen is definitely damaged - something in your backpack put pressure on the middle of your screen and you can see the damage raying out from the impact point.
I'm not trying to add salt to your wound, but the screen on the Kindle is pretty delicate and needs protection from impact. Unless you have a very good case - made out of steel? - the Kindle can not just be tossed into a backpack and carried around where it can be damaged by other hard objects that are carried in the backpack - or damaged if you happen to toss the backpack itself onto a desk, for instance.
Hopefully Amazon CS will be kind to you and send you a replacement even though this is user-caused damage, not due to a defect.
Holly