RE: Is it dead?
Its wrecked for sure, soak it in salt water for a few hours like Jrgunn said and then just throw it out.
Now to find the cause......How old was the pack? Are you using a lipo charger? Do you have a low voltage cut-off? Which pack is it? What setup are you running in the car? Has it ever overheated while running? Have you ever accidentally shorted it?