[Nexus One General] Iggy82:
I personally have tried lots of ROM's but all I really want is the stock ROM with the option to root if I want. After lots of research, I couldn't find a comprehensive tutorial on how to do this. There is of course the GRI40 image available in update.zip format for custom recoveries which is helpful for most. However, if your a bit anal like me, and want the official update directly from Google servers, follow this guide. This might also be helpful for people who can't get into the custom recovery any more.

NOTE: I will not provide help for anybody. This guide assumes you have the Android SDK in order to use adb. There may be other ways of doing this, I am not an experienced programmer, this works for me, it will work for you.

[GUIDE]

Download the following files:

Stock Froyo Image (Contains stock recovery image)

Stock GRI40 Image

Instructions

You first have to revert to stock Froyo image to get the stock recovery back. This is needed to install the GRI40 update ZIP

1. Disable backup my settings under privacy settings.

2. Unzip the original Froyo shipping ROM and put it somewhere you can find

3. Plug in Nexus One with USB to computer (enable USB Debugging)

4. Open command prompt, navigate to SDK folder which contains adb. Type

adb reboot bootloader

(which will boot into the bootloader)

5. Confirm fastboot connection with

fastboot devices

6. Type

fastboot erase userdata

7. Type

fastboot erase cache

*If step 6 and 7 does not work, and if you have a custom recovery installed, you can do a factory data wipe from there. Also perform a dalvik-cache wipe.

Alternately, you can also do a factory data wipe within Android. Settings => Privacy Settings => Factory Data Reset.

8. Go to the directory that you stored your unzipped files from the official Froyo ROM, for ease of use, copy these into the directory containing adb.exe

9. Type

fastboot flash userdata userdata.img

10. Type

fastboot flash boot boot.img

11. Type

fastboot flash system system.img

12. Type

fastboot flash recovery recovery.img

13. Type

fastboot reboot

14. Once phone has started, skip all account setup. Copy the new GRI40 .zip from Google servers to the root of your SD card. Ensure it has been renamed to update.zip if necessary.

15. Reboot into bootloader mode (hold trackball when switching on), select recovery, you will see an exclamation mark with a little green Android.

16. Hold power button and press Vol. Up to see recovery menu. Select 'Apply: Update.zip'

17. After the system boots up and while setting up skip setting up with the google account and you can setup accounts later. This will prevent the phone from pulling down the previous settings (downloaded apps, wallpaper etc) from google.

18. You are done. Enjoy.

If you want to root:

Download the following:

Latest Clockworkmod Recovery

su.zip

Instructions

How to root the stock ROM

1. Download su.zip and copy to root of your SD card

2. Download a recovery image file and for ease of use, copy into same directory containing fastboot on your PC

3. Turn on USB debugging and connect phone to PC

4. Open command prompt, navigate to SDK folder which contains adb. Type

adb reboot bootloader

(which will boot into the bootloader)

5. Type

fastboot flash recovery recovery.img

where 'recovery.img' is the name of your recovery image file (easy thing to do is rename the file to 'recovery.img'!)

6. It will upload, once complete, disconnect you phone from computer

7. On your phone, select Bootloader, then Recovery to boot into your new recovery

8. Now select ‘Apply Update.zip’ and find the su.zip file (Turn off signature verification if using Amon RA)

Note:Custom recovery will be overwritten with the stock recovery on reboot but root privelages will still be in place.