Update AT&T Nexus 6 Build LMY48Z to Project Fi Build MMB29S

How to update the AT&T Nexus 6 to Android 6.0.1 Marshmallow after switching to Project Fi so that its on the OTA update track of Project Fi and not AT&T.


The problem is that even though you are now on Project Fi and have a new SIM in your Nexus 6 it was originally on the AT&T network and has been updated by them. This puts your Nexus 6 at the mercy of AT&T and their update path instead of the more up to date Project Fi path.

At the time of this article Project Fi is on Build MMB29S running Android 6.0.1 Marshmallow with the January security patch while that AT&T Build LMY48Z is stuck on Android 5.1.1 with its last security patch back in December.

Many of us have been hoping that Google and the Project Fi team would have a solution by now to transition those with Project Fi SIM cards into the up to date OTA schedule but alas its not the case. Now the only real options you have is either wait until AT&T updates, if that ever actually happens or flash the Nexus 6 factory image that will get your device free from AT&T. I am going to show you the latter for the sake of freedom.

How to flash build LMY48Z (or any build really) to MMB29S
To be honest this is the process to flash any Nexus 6 build to build MMB29S but for the sake of the article and the issue at hand between previously AT&T Nexus 6 phones moving to Project Fi being stuck at Android 5.1.1 we are offering it up as LMY48Z. The process is simple but you must follow it step by step and take your time.

NOTE: Backup any photos or anything you don’t want to lose because the process will wipe all of your data.

Prepare your Computer

  • Download and install Minimal ADB and Fastboot (download link)
  • Download and install Google Nexus Drivers (download link)
  • Download and unzip the MMB29S factory image to the Minimal ADB and Fastboot directory (download link)

Prepare your Nexus 6

  • Navigate to “settings -> about phone” scroll to the bottom and tap the Build number repeatedly 7 times until it says you are a developer.
  • back up one screen and scroll to the bottom where you will see a new option “Developer Options”, select it
  • turn on “USB Debugging” and “OEM Unlocking” to allow our commands to be ran.

Check your device is found by ADB

  • plug your Nexus 6 into the computer via USB
  • open Minimal ADB and Fastboot via the desktop shortcut created during installation
  • in the command window that pops up type “adb devices” and press enter
  • You will see a string of characters and numbers that say unconfirmed beside it, check your phone and confirm that the computer can have access to the Nexus 6.
  • If no devices show up then you need to install or update the drivers

Unlock the Nexus 6 Bootloader

  • Still in the command window type “adb reboot bootloader” to put your phone in bootloader mode.
  • You will see that the devices bootloader status is locked (if it says status unlocked you can skip to flashing)
  • type “fastboot oem unlock” and press enter and then confirm on the phone as well by selecting yes with the volume buttons and selecting with the power button.

Flash Android 6.0.1 Marshmallow Build MMB29S

  • type “flash-all.bat” and press enter
  • wait patiently as this takes several minutes and may even look like it has frozen at times, just leave it alone until your Nexus 6 restarts on its own.
  • After the phone reboots it will take another long wait on its first boot so again just wait it out.
  • Congrats your Nexus 6 is now free of AT&T

While the idea behind this is to get away from AT&T, those of you on AT&T that want to update to Android 6.0.1 Marshmallow can do so and then just put your AT&T SIM back into the device. For reference I have added a video of myself completing the process for those that get stuck. Of course I have tweaked the process a bit for the sake of the article but its ultimately the same.

I hope this helps those of you on Project Fi get where you should be. This will now allow future updates major and minor push to your Nexus 6 from Project Fi instead of AT&T. If you want to re-lock your bootloader all you need to do it follow the instructions again to the point where you typed “fastboot oem unlock” and just type “fastboot oem lock” instead. If you have questions feel free to reach out and please let me know if I have missed anything as I put it all together here. Good luck!


  1. Thanks Brandon! While I’ve flashed phones for a long time, I do it pretty infrequently and often forget the steps. Your article really helped make this easy and I didn’t have to search a bunch of different places!