The HTC One is currently one of the Taiwanese manufacturer's flagship devices, and this means that HTC should launch the Android 4.4 update on the One sometime in the future. Until then however, you can either wait for the official release, or you can tinker with your smartphone and give it a fresh new look through a custom ROM.

CyanogenMod has recently started launching nightly CM 11 builds for the HTC One, and this guide will allow you to apply the CM 11 custom ROM on the HTC One from AT&T. Keep in mind that CM 11 is based on KitKat, but includes extra features of its own. This also means that the ROM features stock Android UI, so you won't have access to HTC Sense after flashing it. Last but not least, CM 11 is currently under development, in the "nightly" stages of release. As such, you may encounter bugs, but CyanogenMod is expected to launch new, improved "nightlies" in a timely manner.

IMPORTANT – READ BEFORE PROCEEDING:

  • This guide and ROM work only on the HTC One AT&T. Don't attempt to apply it on any other device or One variant, as you could brick your phone
  • Remember that this ROM does not include the Sense UI
  • In order to apply this ROM, you need a rooted HTC One AT&T that runs the latest version of CWM or TWRP recovery
  • During the installation process you are required to factory reset your smartphone. Create backups if needed
  • You can use apps such as "Helium", "SMS Backup & Restore" and "APN Settings Backup & Restore" in order to backup app data, text messages and APN Internet settings respectively
  • Your contacts can be easily backed up by syncing them with your Google account
  • This guide includes instructions on how to create a NANDROID backup of your ongoing ROM
  • As you'll need to connect your HTC One AT&T to a computer, you should enable USB Debugging. Go to "Settings" > "About" > "Software information" > "More" and then tap "Build number" until you gain access to "Developer options". Return to "Settings" > "Developer options" and enable "USB Debugging"
  • It's crucial that your smartphone doesn't remain out of battery during the installation process. It should be at least 70% charged
  • This is an advanced guide and includes unofficial operations. Don't skip any steps, and proceed at your own risk, as you cannot hold anyone responsible if you brick /damage your device

HTC One AT&T – Install Android 4.4 CM 11 Custom ROM via CWM Recovery:

  1. Using your computer, visit this link and download the most recent CM 11 nightly release
  2. Visit this link and download the Android 4.4 Google apps zip file
  3. Using the USB cable, connect your smartphone to your computer
  4. Copy the downloaded zip files on your phone's storage
  5. Once the files have been transferred, disconnect your device form your PC
  6. Access the bootloader menu by pressing and holding the "Volume Down" key. Then, press and hold the "Power" button as well. Once the screen turns black, release the "Power" button but continue to hold "Volume Down" until you gain access to the bootloader
  7. Use the volume keys to highlight "Recovery", and then select the option by pressing the "Power" key
  8. Create a NANDROID backup of your current ROM. Select "backup & restore" from the CWM recovery screen, and follow any additional steps
  9. With the backup in place, go back to the CWM main screen and select "wipe data factory reset" as well as "wipe cache partition". Go to the "Advanced" menu and select "wipe dalvik cache" as well
  10. Return to the main recovery screen and select "Install zip from SD card", and load the CM 11 zip file downloaded at step 1
  11. Select "Install zip from SD card" again, and then load the Google apps zip file
  12. Select "+++Go Back+++" and then "Reboot system now"

NOTE: the first time you reboot your smartphone after a flashing a ROM, you will notice that the process takes several minutes. This is normal. However, if your device does not reboot in 10 minutes, or if it keeps restarting, then you'll need to restart the entire guide. Make sure you've properly factory reset your smartphone, and that you haven't missed any steps

NOTE: in order to return to your previous ROM, you can reboot your device in CWM recovery, tap "backup & restore" and then load the appropriate file

HTC One AT&T – Install Android 4.4 CM 11 Custom ROM via TWRP Recovery:

  1. Visit this link on your computer and download the most recent CM 11 release
  2. Visit this link to download the Android 4.4 Google apps package
  3. Establish a connection between your computer and smartphone via USB
  4. Copy the downloaded zip files on your handset's storage
  5. With the files copied, disconnect your smartphone
  6. Access the HTC One's bootloader. To do so, press and hold the "Volume Down" button, and then press and hold "Power". Continue to hold both buttons until the screen goes black, and when it does, release the "Power" key.
  7. From the bootloader menu, use the volume keys to highlight "Recovery" and press "Power" to select the option. This will make your device enter TWRP recovery
  8. Now, create a NANDROID backup of your ROM. Tap "Backup", mark the type of data that you wish to save and rename the file. Complete the operation by swiping the "Swipe to backup" button
  9. Return to the TWRP screen and factory reset your smartphone. From the "Advanced" menu, you also need to select "wipe cache" and "dalvik cache". Swipe the "Swipe to wipe button"
  10. Once your device is reset, tap "Install" from the main recovery screen and load the CM 11 file
  11. Select "Install" again, and load the Google apps zip
  12. Go back to the main TWRP menu and tap "Reboot"

NOTE: the first reboot will take longer than usual, because you've just flashed a new ROM. If the process does not end in 10 minutes, or if your handset is stuck in a boot loop, then you'll need to redo the guide from the beginning. Make sure you haven't skipped any steps

NOTE: To return to your previous ROM, reboot your handset in TWRP recovery, tap "Restore" and load the NANDROID backup

› See More: HTC One AT&T: Install Android 4.4 CM 11 Custom ROM Using CWM or TWRP Recovery