In my previous article, Installing Jelly Bean on Nexus One, I discussed how I was able to install Jelly Bean on my NexusOne using couple of tools and helper applications.
However, after a couple of days of exploring it, I decided to try to downgrade it back to Gingerbread (mainly because of the Camera issues). This step was even more simple than installing the Jelly Bean on my nexus one. The good thing was that I took the full backup of my Gingerbread before upgrading to the Jelly Bean (using ROM Manager). This backup folder had flash-able images of the system, boot and recovery partitions. So all I had to do to revert back the original version was to run couple of commands in the bootloader mode.
Here are the exact commands (for your info, and my future reference):
1. First you need to boot into bootloader mode. You can do this from key combination of your phone (for Nexus-One, it’s Power+Trackball down), or you can reboot into bootloader mode using the following adb command:
2. Wait for your cell to reboot in bootloader mode, and once you see it, test it by running following command:
If the above command lists your device, then you are good to go forward. Otherwise wait for few more second and/or check USB cable connection.
3. Once the fastboot mode is detecting the device, you can flash your Image and System flashable images using following commands:
fastboot flash boot boot.img fastboot flash system system.img
4. The next step is to simply clear your cache and user-data to avoid any problem with previous ROM data.
fastboot erase userdata fastboot erase cache
5. And at last, simply reboot your phone:
If everything went well, you should be able to see your previous version without any problems.