It's not very well known, but you can burn the coffin to kill a vampire. They did this in the middle ages. Apparently the vampires made all kinds of crazy sounds, which proved they were vampires.
"Oh, god! I'm burning! Somebody help!"
"What is that horrible screeching sound coming from the coffin?"
"Oh, Jesus Christ! It hurts!"
"Their screaming only proves they're vampires. Vampires are weak to fire."
"Let's light you on fire and see how you react!"
*Embers land on spectator.*
"Ow. That hurts."
"The embers hurt him! He's a vampire! Kill the vampire!"