My system: Windows x64, Nexus One, Android version 2.1 update1, Build number ERE27
- Download the Android 2.2 firmware from here.
- Rename the ‘signed-passion-FRF50-from-ERE27.1e519a24.zip‘ file to ‘update.zip‘ and copy it to SD card.
- Power down Nexus One.
- Hold down the ‘Volume Down’ button and press the ‘Power’ button.
- In the list, press the ‘Volume Down’ button, scroll down to ‘recovery’ and press the ‘Power’ button.
- When the triangle with an exclamation point symbol show, press the ‘Power’ and ‘Volume Up’ buttons at the same time.
- In the next screen, show the error: “E:Can’t open /cache/recovery/command“, don’t worry about it, press ‘Volume Down’ button, select ‘Apply sdcard:update.zip’ from the menu and click ‘Trackball’.
- Waiting for update run their course
After the Nexus One auto reboot, Click ‘Settings’ and ‘About phone’, Android version: 2.2, Build number: FRF50