The CyanogenMod team has released a Nightly CM 12.1 build for the Samsung Galaxy Nexus smartphones. If you want to install such custom ROM on your phone, then you should use the instructions listed in this post.
The new CM 12.1 custom ROM is based on the AOSP Android 5.1 Lollipop ROM. It packs all the stock Lollipop features, as well as several other elements designed by the CyanogenMod developers.
Before starting the installation of this new Android 5.1 custom ROM you should first read the preparation guide below:
- use this post only with the Samsung Galaxy Nexus phone.
- do not try to flash the files that you will find in this post on any other different Android device.
- your Galaxy Nexus device has to be rooted and it should be running a custom ROM like CWM or TWRP.
- the installed custom Recovery has to be upgraded to its latest version, so that it will support the newest Android 5.1 custom ROM installations.
- if your device is not rooted, then you cannot flash any new ROM on your device.
- in the tutorial part you will find two extra preparation steps like the NANDROID ROM Backup and the Factory Reset ones.
- do not skip these steps.
- the NANDROID ROM Backup creates a full restore point for your device, one that you can use in case the new CM 12.1 Nightly ROM doesn't boot in normal mode.
- the 'factory reset' process will wipe the system memory partition, but it won't delete any data from the internal storage.
- if you need to save some data from installed apps, the you should use Helium.
- don't use Titanium Backup with CyanogenMod 12.1 ROM as it isn't supported by it.
- use this post only if you are an advanced user.
- we cannot be blamed in case you brick your device nor in case you lose any important files during the installation process.
- read the entire post and make sure not to skip any steps.
Now that you know all of the above you can continue to the next part of this post.
Note that you can continue installing new CM 12.1 Nightly ROM builds using the CyanogenMod Updates menu from Settings> About Phone section.
The Nightlies will most probably be released several times a week, which means that most bugs that found in the first CM 12.1 Nightly build will eventually be fixed once a whole month of Nightlies will be made available for download.
How to flash CM 12.1 Android 5.1 ROM for Samsung Galaxy Nexus:
- Download the CM 12.1 Android 5.1 ROM from here.
- Download Gapps for Android 5.1 ROMs from here.
- Connect your Galaxy Nexus to your PC and move both zip files on to its internal storage.
- after the files are moved to your phone you can disconnect it from computer.
- do not extract the archived files.
- Power off the phone.
- Now boot it in Custom Recovery Mode.
- Create a NANDROID ROM Backup for the installed ROM:
- CWM: select 'backup and restore'.
- TWRP: select 'backup' option.
- set a name for this file and confirm process.
- Start the factory reset of your Galaxy Nexus phone:
- CWM: select 'wipe data/ factory reset'.
- TWRP: select 'wipe'.
- confirm the factory reset.
- Now you can begin the CM 12.1 installation:
- for CWM-based Recovery select 'install zip from sdcard', then 'choose zip from sdcard'.
- for TWRP select 'install' option.
- Find CM 12.1 Nightly zip and confirm the installation process.
- After the new custom ROM is done installing you can flash the Gapps zip, too.
- Reboot your phone in normal mode when all the new firmware and gapps files are done installing.
- Use your default Google account in order to regain control over your device once again.
If installation fails, then you can try to repeat installation after you've made sure that your phone meets all requirements listed above the tutorial.
In case you need more help completing this guide, then you can tell us in comments field below.