May 252010

My system: Windows x64, Nexus One, Android version 2.1 update1, Build number ERE27

  • Download the Android 2.2 firmware from here.
  • Rename the ‘‘ file to ‘‘ 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’ 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