Hi there! I understand you're having trouble getting the Michaels Stores app to open on your iPhone running iOS 18.5. Let's work through this together.

To start, can you tell me if the app shows any error message when you try to open it, or does it just stay on a blank screen or immediately close? Also, is the app completely unresponsive, or does it get partway through loading?

Meanwhile, here are some initial steps we can try to get the app working:

1. Restart Your iPhone: Sometimes a simple reboot can clear temporary glitches. Hold the power button and slide to power off, then turn it back on.

2. Check for App Updates: Open the App Store, tap your profile icon at the top right, and scroll to check if there’s an update available for Michaels Stores app. Installing the latest version can fix issues.

3. Force Quit and Reopen the App: Swipe up from the bottom of the screen and pause (or double-click Home button if you have one), then swipe the Michaels app off the screen to close it. Then reopen the app.

4. Delete and Reinstall the App: If the above doesn’t work, tap and hold the app icon until options appear, select "Remove App," then go to the App Store and download it fresh. This can clear corrupted data.

After you've tried these, let me know how it goes or if you’ve already done any of these steps. We can then look into more advanced troubleshooting or check for server-side issues if needed.

Are you able to try these steps now?