how did the characters from nightmare before christmas die

The characters from Nightmare Before Christmas were actually brought back to life by Santa in an effort to keep Halloween from becoming too popular. Santa wanted to make sure that Christmas was the most important holiday, so he took the characters from Nightmare Before Christmas and transformed them into harmless, friendly versions of themselves. However, the original versions of the characters were killed by the demons who inhabited the nightmare world. The demons were angry that Santa had taken away their beloved characters and they wanted to get them back.