It took me 2.5 hours to find all the information to downgrade my wife's Nexus S to 2.3.6.
Update: I Tried this on I9020T. I flashed 2.3.4 first because that's the first signed zip and then updated to 2.3.6.
Note: This method requires to unlock phone's bootloader to flash custom recovery
- Backup your sd-card (I also backed up my call logs, sms, mms and bookmarks.)
- Download 2.3.X version that you want flash using this link
- Prepare your computer for fastboot command using this link, If you have any driver issue for fastboot use this link.
- Unloack boot-loader using this link, follow the Unlock boot-loader section.
- Now reboot your phone and copy 2.3.X zip on your sd-card.
- We need to flash custom recovery, so follow the Installing the ClockworkMod Recovery Image sections from this link.
- Select Recovery from fastboot
- Select Wipe data.
- Select Install zip from sd-card.
- Select Reboot system now.
- Restore sd-card from backup (be carefull I didn't not restore those .android-XXXX folders, you might get weird errors).
- Now you have Gingerbread running on your Nexus S, if you care you can lock the bootloader again by turning your phone into fastboot and typing following command. Locking won't wipe out your sd-card so don't worry.
Update: I Tried this on I9020T. I flashed 2.3.4 first because that's the first signed zip and then updated to 2.3.6.
