Hi there! I'm here to help you with your Santander app issue. I understand how frustrating it can be when an app won't open, especially after you've already tried reinstalling it. Let's work together to solve this.

1. Check for System Updates: Sometimes, system updates can affect app performance. Go to your device settings, scroll down to "System," and check if there are any updates available for your Android OS.

2. Clear App Cache and Data: Clearing cache and data can help resolve issues with apps. Here's how:
- Go to Settings on your device.
- Select "Apps" or "Applications."
- Find and tap on the Santander app.
- Tap on "Storage," then select "Clear Cache" and "Clear Data."

After that, try opening the app again.

3. Reboot Your Device: Restarting your phone can often fix temporary glitches. Just turn it off and on again, then try launching the app once more.

4. Check Your Internet Connection: Ensure your internet connection is stable and working properly. You can try using a different Wi-Fi network or switch to mobile data.

5. Check Permissions: Make sure the Santander app has all the necessary permissions enabled. You can do this by going to the app settings in the "Apps" section and checking under "Permissions."

If you've tried these steps and the app is still not opening, there might be a temporary issue with the Santander server itself. You might want to check the Santander support community for any outage reports or updates.

Are you satisfied with the solution I provided, or is there anything else you'd like assistance with?