Upgrade Android 4.4.2 To 9.0 [better] Link

The first boot cycle after upgrading can take anywhere from 5 to 15 minutes. The system is building new cache databases for the updated environment. Common Issues and Solutions

You gain access to gesture navigation, dark mode, adaptive battery management, and a completely refreshed user interface. Risks and Important Prerequisites upgrade android 4.4.2 to 9.0

Turn on and OEM Unlocking inside Developer Options. The first boot cycle after upgrading can take

This is the safest method, but the least likely to work for a jump from 4.4.2 to 9.0. It's always worth checking first: adaptive battery management