HTC One is on display at a store. (Reuters)Reuters

After months of delay, CyanogenMod has finally released a stable CM12.1 firmware to HTC One M7 model.

The new CM12.1 (snapshot) is said to come with numerous bug-fixes and value-added features to improve user-experience on the HTC One M7. "The CM12.1 release marks our first Android 5.1.1 release, which brings our IMAP idle support, SDK v1 release and the security fixes mentioned previously," said a CyanogenMod community representative.

Users are advised to pay close attention to the CM release version and check whether the version of their third party installs (kernels, mods, gapps, etc) are compatible to the custom ROM.

Read more: Android Stagefright Bug: How to Minimize its Vulnerability on phone and Everything You Need to Know

Things to remember before installing CyanogenMod CM12.1 custom ROM:

  1. Installation of custom ROM requires clearing of memory in the smartphone, so make sure to back the data by installing Clockwork Mod (CWM) Recovery/ TWRP in the smartphone
  2. CyanogenMod CM12.1 [Snapshot] Android 5.1.1 Lollipop custom firmware has to be installed on the HTC One M7 model only ; if tried on other devices, they might get bricked [To check your device model: Go to Settings >> About phone >> model number]
  3. Make sure the device is rooted before going forward for custom ROM installation
  4. Make sure you have installed USB drivers on the PC, or else your smartphone (HTC One M7) will not be recognised by the computer.
  5. Make sure your device has more than 80 percent battery, or else there is a chance of the smartphone getting temporarily bricked if the installation process is interrupted mid-way.

[Disclaimer: This procedure is very technical and should be performed by a person with sound knowledge of rooting (or manual software installation) Android devices. If the step-by-step installation process is not followed properly, there are chances of the smartphone getting bricked or being permanently irreparable. IBTimes India cannot be held responsible for any damage or claims from readers if the procedure does not yield the required results or if the smartphone is bricked. Hence, users are advised to proceed with caution.]

CyanogenMod CM12.1 Downloadable files:

HTC One M7 CM12.1: HERE [Build date: 01/09/2015]

Cyanogen Recovery: HERE

Google Apps: HERE

Tutorial: Step-by-step Installation Guide for CyanogenMod CM12.1 [Stable] Android 5.1.1 Lollipop Custom ROM Snapshot on HTC One M7 (GSM) model:

Step 1: After downloading the new CM12.1 custom ROM and Google Apps to the PC, connect HTC One M7 to the Computer via USB cord.

[Note: Before plugging the phone to the computer, be sure that you have installed the USB driver software, if not, click HERE to download the firmware]

Step 2: Place Android 5.1.1 Lollipop zip file and Google Apps files in the phone's SD card memory. [Note: Users are advised to paste the zip file in SD card root, not in any other folder.]

[Note: Before installing the custom software, be sure that the device is rooted and has installed ClockworkMod Recovery tool.]

Step 3: Place boot.img file in to the android-sdk-windowsplatform-tools directory

Step 4: Turn off the device and disconnect from the PC.

Step 5: Perform the regular Bootloader mode sortie, by press holding 'Volume (Down)' and 'Power' buttons.

Step 6: After entering the Bootloader mode (on the phone), go to android-sdk-windowsplatform-tools directory (on the PC) and open Command prompt, then type in: 'fastboot flash boot boot.img' and press enter.

(To enter Command prompt: Shift + right-click >> open Command Prompt)

Step 7: Type - 'fastboot reboot' and press enter. Then, follow instructions displayed on the screen. Select BOOTLOADER option to enter Recovery Mode.

Step 8: After entering the Recovery mode, clear the phone memory, by choosing 'wipe data/factory reset' [Note: use Volume keys to navigate and power button to select options, while operating under Recovery Mode]

Step 9: Clear the cache memory by selecting 'wipe cache partition'.

Step 10: Go back to ClockworkMod recovery, and select 'advanced' and tap 'wipe dalvik cache' [Note: This step is optional, but many recommend the procedure so that user will not face boot loops or any other errors in the middle of custom ROM installation]

Step 11: Come back to main recovery screen and then tap 'install zip from SD card'

Step 12: Tap 'choose zip from sdcard' and go to Android 5.1.1 Lollipop ROM .zip file in SD card and enter the installation process. Repeat the same procedure for Google Apps [Note: use Volume keys to navigate and power button to select options]

Step 13: Once done with the installation process, navigate to '+++++Go Back+++++' and re-start the device by opting 'reboot system now' seen in the recovery menu.

Your device (HTC One M7) will take at a few minutes (only for the first time) to complete the booting process.

Head to Settings >> select 'About phone' to confirm the installation of CyanogenMod CM12.1 [Stable] Android 5.1.1 Lollipop custom ROM.