One S variant of HTC can be updated to Android 4.4.4 KitKat using a custom ROM stable Build like the CM 11 M12 ROM. Use this tutorial if you want to learn how to successfully install one of the most popular KitKat custom ROMs.

The CyanogenMod team has released the M12 Snapshot build of CM 11. This might possibly be one of the final KitKat builds released, as they will start working on CM 12, a new CyanogenMod OS that is based on the newest Android 5.0 Lollipop. Learn more about this release here.

Before starting the installation process you should read the preparation guide below:

  •  use this guide only with the HTC One S smartphone.
    - do not attempt to update any other devices with the files that you will find in this article.
    - if you install the CM 11 M12 build for One S on any other HTC device, then you will end up bricking the firmware.
  • the One S device that you're about to update with CM 11 M12 ROM needs to be rooted and running the latest CWM or TWRP custom Recovery build.
    - both these custom recoveries will work with this post.
  • in the 'how-to' part of this article you will find two more preparation steps that you shouldn't skip: NANDROID ROM Backup and Factory reset.
    - the NANDROID Backup process will create a complete restore point for your device, one that you can re-install in case the new CM 11 M12 ROM doesn't boot in normal mode.
    - Factory Reset will wipe all the data installed by the previous ROM, this process allows the new ROM to boot successfully.
    - Factory Reset only wipes data from the system partition, the internal storage contents will not be affected by this process.
  • in case you want to save data from installed applications, then you should use the Helium app for Android.
    - Contacts data can be synced with your default Gmail account.
  • check your device's battery charge level and make sure that it is over 50%, this will prevent the device from powering down during installation.
  • this is a guide for advanced Android users, do not blame us in case you end up losing any important data in the process.
  • check the battery charge level of your device and make sure that it is over 50%, this will prevent the device from powering down during flashing process.
  • read the entire post and don't skip any steps we've listed in the tutorial.

Since you've read all of the above you can now continue to the next part of this post in order to learn how to successfully install the new ROM.

How to flash CM 11 M12 Android 4.4.4 ROM for HTC One S:

  1. Download the CM 11 M12 Snapshot zip here.
  2. Download Gapps for Android 4.4.x custom ROMs here.
  3. Move both of these files to your phone's internal storage.
    - if you've used the phone to download these files directly, then you can skip this step.
    - do not unzip the files.
    - disconnect the phone from PC after the files are transferred.
  4. Power off the HTC One S and then boot it in CWM / TWRP custom Recovery Mode.
  5. First thing that you need to do is to create a full NANDROID Backup:
    - for CWM use the 'backup and restore' option, while for the TWRP version you need to use the 'backup' option.
  6. Next you have to apply a Factory Reset:
    - CWM: select 'wipe data/ factory reset' while for TWRP you have to use the 'Wipe' function.
    - confirm this process.
  7. Start the installation process of CM 11 M12 Snapshot ROM:
    - CWM: select 'install zip from sdcard', then 'choose zip from sdcard'.
    - TWRP: select 'Install' option.
    - find the CM 11 M12 Snapshot ROM file and confirm process.
  8. After the new ROM is installed you need to install the Gapps zip, too. Use the same actions as in step 7 in order to find Gapps zip and complete its installation.
  9. Reboot the HTC One S in normal mode after all files are flashed with success.
    - note that the CM 11 M12 first boot process takes a while before it loads all files.
  10. Use the CM profile or your Google account info in order to take complete control over your smartphone.

These were all the steps that you had to follow in order to complete the installation process of CM 11 M12 ROM for your HTC One S smartphone.

For extra help use the comments field.

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