A struggling rock band must fight through petty rivalries, a dickhead manager and the zombie apocalypse, saving their band and the world on their way to the top.

No need for ritual in this instance, zombies are a trope, best to jump into the action - how the good guys choose to fight them. The uniqueness of the action the main characters take to fight the zombies in a zombie flick is what will make it interesting. All the rest of the stuff; obnoxious managers, love interest and inner group tensions are a given and need not be elaborated on in the logline.

My try:
After a zombie apocalypse a rock band discover their unique sound kills zombies they must now save humanity while climbing to the top of the charts.

26 words.

The other reviewers are correct. The core idea seems to be "When the Zombie Apocalypse destroys their world, an aging rock band must find their own unique sound to save the world." or something similar.

What Moses99 said.?The logline needs a unifying framework in terms of a singular objective goal.

It does need a specific goal that the story revolves around. You've got the bones, people and drama between them.

How do they save the world? Is it a huge story "World War Z" or small "Shaun of the dead".

This is just a series of disconnected scenes, not a story which is what a logline is supposed to tell. ?Link them and tell us their specific goal and how these things play in because I can see what you're going for but just try and tie it all together.

This is just a series of disconnected scenes, not a story which is what a logline is supposed to tell. ?Link them and tell us their specific goal and how these things play in because I can see what you're going for but just try and tie it all together.