Hi there! I’m sorry to hear that your Letterboxd app won’t even open on your iPhone running iOS 18.5. I want to help you get it up and running again. To start, could you share if you’ve already tried restarting your device or force quitting the app before opening it again? Also, if you’ve tried reinstalling, please let me know.

While waiting for your details, here are some quick steps that often help resolve app launch issues:

1. Restart your iPhone: This clears temporary glitches that might affect the app.
- Press and hold the side button and either volume button until the slider appears. Slide to power off, then turn your phone back on.

2. Force quit and reopen the app:
- Swipe up from the bottom of the screen and hold briefly (or double-click the Home button if your iPhone has one), then swipe up on the Letterboxd app preview to close it.

3. Reinstall the app:
- Press and hold the Letterboxd app icon until you see the option to delete it. Delete and then reinstall from the App Store.

If none of these bring the app to life, there could be a deeper issue, possibly with the app version or a conflict on iOS 18.5. Sometimes, app updates introduce bugs that require a patch or waiting for a fix from the developers.

Have you noticed if the app either crashes immediately or just stays stuck on a loading screen? Also, are other apps working normally on your phone?

Let me know how these steps go, and we can dig further if needed!