: Go to Settings > About Phone and tap "Build Number" 7 times to unlock Developer Options.

: Depending on your brand, you will need software like ODIN (Samsung), SP Flash Tool (MTK devices), or ADB/Fastboot for Nexus. 4. Installation Steps (General)

: Sites like 4PDA often host mirrors and custom builds for older hardware. 3. Preparation & Tools

Установка Android 5.0 Lollipop: инструкция от mobiltelefon.ru