The plot didnt make any sense.
Its a huge plot hole that she wasnt really a witch, just an innocent victim.
First, the Puritans of New England did not use magic sigils nor perfomed rituals. These things were considered demonic and were performed only by warlocks and witches.
Second, the Puritans of New England did not burn witches. They hanged them.
Third, is it more probable that the Puritans had the power to transform a simple innocent girl through a magic ritual into a immortal zombie with supernatural powers that could restore its flesh by sucking the life force of others than witches actually existing? Makes no sense.
Fourth, if the corpse didnt want to feel all this torture again, why didnt she create a hallucination before they started opening her?
Fifth, if she was burned and was able to restore her body, why didnt the sigils fade away with the new skin?
In general, it was an ok horror/thriller movie. When they first said she was a witch, I found it pretty cool. But when they revealed that she was just a poor innocent girl, I started laughing and ruined the whole experience for me.