Hi there! It's unfortunate to hear about the battery issue you're experiencing with your Redmi Note 9. Battery drain problems can be frustrating, but there are a few alternative solutions you can try:
1. Check for background apps: Make sure there aren't any apps running in the background that may be draining your battery unnecessarily. You can check this by going to Settings > Battery > Battery Usage.
2. Enable battery-saving mode: Redmi devices usually come with a built-in battery-saving mode that can help extend battery life. You can activate it by going to Settings > Battery > Battery Saver.
3. Disable unnecessary features: Turning off connectivity features like Wi-Fi, Bluetooth, and GPS when you're not using them can help reduce battery drain. You can access these settings in the quick settings panel or in the Settings app.
4. Clear cache: Sometimes, accumulated cache files can cause battery drain issues. Clearing the cache can help improve performance and battery life. You can do this by going to Settings > Storage > Cached data.
5. Factory reset: If none of the above solutions work, you might consider performing a factory reset on your device. This will erase all data, so make sure to back up important files before proceeding. Go to Settings > System > Reset > Erase all data.
If none of these solutions resolve the issue, it's possible that the battery replacement might not have been done correctly or there could be a hardware problem. In that case, I would recommend contacting Xiaomi support or taking your device to an authorized service center for further assistance. They will be able to diagnose the issue and provide the necessary solutions.
I hope this helps, and good luck with resolving the battery problem on your Redmi Note 9!
PH