Hi there! I'm here to help you with the Best Fiends app issue on your Kindle device. It sounds like the app isn't opening, or it's crashing when you try to open it. Let's work through this together!

First, could you let me know if you're seeing any specific error messages when trying to open the app, or does it simply close without any notification?

In the meantime, here are a few steps we can start with to troubleshoot the issue:

1. Check for App Updates: Ensure that your Best Fiends app is updated to the latest version. You can do this by going to the Google Play Store, searching for Best Fiends, and seeing if there's an "Update" button available.

2. Restart Your Device: Sometimes, a quick restart can help refresh the system and clear temporary glitches. Simply hold down the power button and select "Restart."

3. Clear App Cache:
- Go to Settings on your Kindle.
- Find Apps or Application Manager.
- Locate Best Fiends and tap on it.
- Tap on Storage, then select Clear Cache.

4. Look for Available Storage: Make sure there’s enough storage space on your device. If your storage is running low, it can cause apps to misbehave. You can check this in Settings > Storage.

5. Uninstall and Reinstall the App: If the above steps don’t work, you might want to uninstall the app and then reinstall it from the Google Play Store.

If you've already tried some of these steps or if the problem continues, please let me know so we can explore further options!