Hello! It sounds like you're having some issues with your Huawei Nova 3i after having the LCD replaced and experiencing battery drain problems. Here are some steps you can try to recover your phone:
1. Restart the Phone: Sometimes, a simple restart can fix minor software glitches. Press and hold the power button until the phone restarts.
2. Charge the Phone: Make sure to charge your phone using the original charger and cable. Allow it to charge for at least 30 minutes before attempting to turn it on again.
3. Enter Recovery Mode: If you're unable to access Recovery Mode by pressing the necessary buttons, you can try using ADB commands on a computer. Connect your phone to a computer with ADB installed and use the command "adb reboot recovery" to enter Recovery Mode.
4. Factory Reset: If you can access the Recovery Mode, you can try performing a factory reset. This will erase all data on your phone, so make sure to back up important information if possible.
5. Replace the Battery: If the technician suggests replacing the battery, it might be worth considering, especially if the battery is causing the drainage issue. A new battery could potentially resolve the problem.
6. Seek Professional Help: If you're still unable to resolve the issue, it's best to consult with a professional technician or Huawei service center for further diagnosis and repair.
I hope these suggestions help you recover your Huawei Nova 3i. Good luck!