When a hyper-sexualised girl band becomes trapped by a psychopathic religious woman, a pop singer must kill her band and manipulate her captor to escape.

Yes about the crazy woman - properly motivating her will help to motivate the protagonist. Darth Vader's motivation increased Luke's obstacle, and in turn made his journey more interesting. Same with Max Cady in cape fear and Gus in Breaking Bad.

But the quality of motivation counts as well. Perhaps the crazy woman's daughter, a die hard fan, recently became a teenage stat by falling pregnant during a concert and the mother is out for revenge.

Since the religious woman is the prime mover, the one who boots up the story by taking the band hostage, yes, find out what the religious woman wants -- the "why?" ? There ought ?to be a ?"why" otherwise the conflict and suffering is essentially meaningless, gratuitous. ?The audience doesn't have to agree with the "why", just accept it as credible.

Which is another way of asking: what is the core value or idea you wish to explore in this story? ?What's your dramatic point? ?Devoutly religious people find wanton sexual behavior sinful. ?Why does this one over react, go beyond mere moral revulsion?

You had me at hyper-sexualisde...

Unfortunately, as the others have said, the inciting incident and motivation don't stack up.

Aaron Sorkin interestingly says that he never starts with a character, rather he starts with a need and means. First he comes up with a good goal, then he comes up with the particular tactic the character will take to achieve the goal. I believe the same type of thinking could help in this instance.

What is it that a singer in a band such as this could really want? NAY, could really need? Right now her motivation for achieving her goal is vague and her goal of survival rather generic.
How would that goal be achieved? It's this choice of tactic to achieve the goal that will define the character for you.