Come up with a new ending.
Oh god. Endings come in two forms: they succeed or their fail. So, why would I be writing a book where they all fail? I’m sure some writers do and I applaud them because I don’t have the stomach for that. For the purpose of this exercise, let’s say I do. Elements ends with the girls discovering the truth about their powers but it’s too late and they all perish in their crusade against their enemies. Bring tissues.