1) Check your return policy. Within the time limit? No restocking fee? Return it and tell them you're going with another vendor.
2) If you really want to push it, and used your credit card, send it back and contest the charge under personal dissatisfaction. It will take 3 months of forms but you'll avoid paying.
3) Just forget about it. This is my personal recommendation. The dead pixel will bug you now because you are fixated on it and want your new TV to be perfect.
Just sit back, have a beer, and watch something engrossing. Play a good game. Get your mind off of it. Soon, you will forget it's even there. Every know and then, you'll steal a glance, but that just means you need another beer.
Remember - you may have lost one, but you have 2,073,599 left.