Possible Duplicate:
can't update, can't do a factory reset

My Phone (Nexus S) keeps pestering me to update the OS. But, every time I try, it restarts, displays the cute robot error screen and doesn't come back on until I take out the battery and restart it. I would just leave it but I'm still running Android 2.3.4, and it's time.

Any way of updating the OS other then clicking OK when it asks?

I'm not really sure what more info I can give you guys, ask and I will tell

  • Have you ever not pulled the battery out and just left it overnight attempting to update? – Blundell May 10 '12 at 22:08

When you see cute robot with the red triangle, press power + volume up together to get to the recovery menu, and select "update from /cache" or something similar you'll see there. Then the update process starts and, most probably, gives you some error messages about what's wrong with your phone.

If you have ever changed any system files, update process might require you revert them to the original condition before upgrade, otherwise patches cannot be applied properly.


If you don't mind a factory reset, you can flash the latest factory image from the bootloader (fastboot).

If you're on Linux, instead of installing the SDK, you can use Replicant's build of fastboot.


This a solution to bring your device to a stable, stock, factory default state.

NOTE: this will wipe your device (not the SD card) and return it to stock, unrooted factory defaults.

  1. Download one of these two files:

    • This file if you want to restore to Gingerbread
    • and this zip file if you want to restore to the OTA 4.0.4 (Ice Cream Sandwich) latest update.
  2. Extract the file you downloaded to your computer, in a location you remember.

  3. On your phone, enable debugging

    • this is usually found by going to the home screen, then pressing Menu and choosing Settings->Applications->Development and check the USB debugging option
  4. Plug your phone into your computer

  5. Locate the run.bat file in the location where you extracted the .zip file

  6. Run this file and wait for the process to finish.

  7. You're done! Reboot and enjoy!


Some of the Nexus S come with locked bootloaders and cannot be upgraded without rooting because of this.

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