Writing a treatment / repurposing IP-based story into original

I haven't seen Zack Snyder's Rebel Moon yet, but was inspired by how he repurposed his rejected Star Wars pitch into an original. In 2007 I wrote a spec script for a reboot of Power Rangers, and of course Lionsgate beat me to an eventual movie. I decided I could still do something with it. I remember a lot of what I wrote then (and I probably have that old script somewhere). I went back and tried to remember everything I wrote, all the ideas I had, any changes I needed/wanted to make. I decided instead of vomiting everything into a script, it would be better if I just wrote a treatment.

I don't have much experience with treatments or scriptments, but I did experiment with writing one previously for this very same project. But since my script was pretty much fleshed out anyway, it seemed redundant. This time around, a treatment seemed like the best way to brainstorm. I often have all my ideas in my head (sometimes the ending) and write my scripts blindly, seeing where they take me. Sometimes I write down ideas and basic loglines before I actively work on them.

I've been googling around to find the best articles and manuals about how to write a treatment and/or scriptment, with or without examples. It's been fun to let my creative brain run wild. My treatment is currently four pages, half of that being the character list with introductions and bios.

I've learned a bit from articles from Masterclass, Studio Binder and No Film School.