"The dealer where the bike is is not where I purchased it. But the response I was given was that bmw will not help with this. The total estimate I was given was...get this... $20,683.00."
First, doesn't matter where you purchased it. You can go to any authorized BMW Motorrad dealer.
Secondly, how on earth can it cost $20k to repair an $11k bike? I'd be eager to quote that figure to BMW and see what they say. And I'd put zero credibility in the dealer's comment that BMW will not help. They have no clue what BMW will do. BMW will decide. They're at 800-831-1117. BMW has power over the dealer. An attorney will have to win power in a drawn out process that you cost you lots of money, IF you win.
I've read many stories on this forum where BMW has gone to the wall and beyond for customers. Particularly in situations like yours (might be) where the chain tensioner failed and killed the engine. That happened a lot and BMW had a major recall.