If you’ve got a Google Nexus One and you haven’t unlocked it, rooted it, and/or flashed a custom ROM on it, there’s an update for you!
If, on the other hand, you have done any of those, this update isn’t for you. Don’t proceed any further.
This update is coming OTA (over-the-air), but if you haven’t gotten it yet and want to manually update, here’s how you do it.
1. Download the 2.2.1 firmware from Google.
2. Rename it to update.zip (for you newbies, update.zip.zip is wrong), and place it on the root of your microsd card.
3. Turn off off your Nexus One.
4. Hold the VOLUME DOWN button and press the power button once to boot it back up.
5. When your phone displays the “skating Androids screen” highlight “recovery” and press the POWER button to select it.
6. When you see the “exclamation mark in a triangle” press the POWER button and the VOLUME UP button at the same time.
7. When presented with the menu select “Apply sdcard:update.zip”.
8. When you see “Install from sdcard complete”, select “reboot system now”.
What does this update give you?
In a nutshell, we don’t know. Google’s been fairly quiet about it. We suspect it’s a roll-up of various patches and tweaks. You’ll be able to tell you’ve got it when you see these numbers on your phone’s About screen.
Android version: 2.2.1
Baseband version: 32.36.00.28U_4.06.00.12_7
Kernel version: 220.127.116.11-27240-gbca5320
Build number: FRG83
(Source: Android Central)