We have just posted the steps to manually download and install Android 2.3.3 Gingerbread on Nexus S. Now, we are presenting here the steps to manually download and install Android 2.3.3 Gingerbread on Nexus One.
How to Manually Update Nexus One to Android 2.3.3 Gingerbread
1. Download Android 2.3.3 Gingerbread Update for Nexus One
2. Rename the downloaded zip file to update.zip
3. Copy it to root of your micro-sd card.
4. Boot your device in recovery mode by holding the trackball and pressing once on the power button.
5. Select Bootloader and then select Recovery
6. Let the device reboot (wide display an exclamation point) and then press the volume up and power button at the same time
7. Finally select Apply sdcard:update.zip with the trackball.
NOTE: You may have to soft reset a couple of times after this.