updates - Manually upgrade Galaxy Nexus 4.0.4 (yakjuxw) to 4.1

I have a Galaxy Nexus (maguro/yakjuxw) with Android version 4.0.4. I saw the new features in 4.1 so i want to update, but i don't think an OTA will be available anytime soon. So, I'm considering manually updating. AFAIK, I will need to switch to the yakju firmware that gets updates directly from Google.

That being said, I have some questions:

• Is the firmware the same as the OS? I always thought firmware is something like BIOS, UEFI, coreboot etc. and OS like Windows, GNU/Linux etc. But i have a feeling the terms are used slightly differently in the Android world. This is because the updates guides I found usually show how to flash firmware.


• Will such an upgrade require rooting the phone?


• Will this void my warranty?


• I know a Google search will yield many guides on how to do this, but I'd appreciate it if an experienced user could provide a link with the guide he/she considers to be the best (most complete, safe etc.)

Answer

• 
  

  Firmware, in this case, means the OS, since it's a preinstalled part of the core system.

  
  



• 
  

  The method I used does not require root, but it's possible to root at the same time. I didn't.

  
  


• 
  

  This depends. In most cases, unlocking the bootloader voids your warranty if the warranty is read and interpreted letter-to-letter. However, you could install an official firmware and relock the bootloader to try to bypass this.

  
  

I've upgraded my yakjuxw with this guide's method #2. Everything went perfectly except for a few little tricks.

First of all, if your phone is completely unmodified, you need to unlock your bootloader. This can be done by booting into the bootloader as explained in the post, and running fastboot oem unlock, navigating to "Yes, unlock bootloader" with the volume keys and confirming with the power button.

NOTE: This will clear your phone, so you'll need to copy the necessary files to your phone after this!

After this, reboot once so that the partitions are mounted correctly in CWM later.

Now follow the guide carefully, and you should be able to upgrade (almost) without any problems. My phone got stuck while booting for the first time, so after 15-20mins I rebooted the phone (yanked the battery) but had no adverse effects.

At least my phone got the official 4.1.1 update today, so check for that after your first boot!