When mine went bad I thought I was going to have the battle of the century with Best Buy. I was wrong. I had a new TV on my wall five days after my first contact about warranty replacement. I can't say you'll get the same results but this is what worked for me.
Contact Best Buy head office about warranty, not the store you bought from. I think I emailed them and they got back to me the next day. They gave me the name of the local company that did warranty service for them. If you can get the service company to agree that you should get a replacement set, you will have no problems. The guy I talked to didn't even come to see the set, he just asked me questions over the phone and said, yup, you need a replacement panel. I'll write up an estimate that's more expensive than buying a new set and BB will give you a new TV. Head office called back the next day and asked which store I wanted to deal with and a day later that store had all my info and was ready to work with me.
They gave me a credit for the lowest amount they had sold the set for, but I've read where some folks got full purchase price credit. Don't be afraid to politely push a little to get them to give you a better deal.
Be polite, it will get you farther and figure out what TV you would like to get as a replacement before you start to deal with the local store. That way you will have a goal in sight and a price range that you are willing to spend and can hopefully talk them in to giving you a credit in that amount. I wish I had pushed a little harder but at the and of it all I went from the bottom of the line 42" Toshiba (at the time) to the top of the line 46" Toshiba (at the time) for a little under $300.
Good Luck, keep us posted.
Capitalization is the difference between.. "I had to help my Uncle Jack off a horse" and I had to help my uncle jack off a horse.