While CyanogenMod team is busy working on the official Android 5.1 Lollipop based custom firmware for HTC One M8, you can already flash it on your device thanks to an XDA member. This is an unofficial version so please don't go forward if you don't have any previous experience of using all sorts of custom ROMs. Here are the steps to update HTC One M8 to Android 5.1 based CM 12.1 custom ROM.
Prerequisites to update HTC One M8 to Android 5.1 CM 12.1:
- Backup any important data from your HTC One M8 as a complete wipe will be required during the flashing process.
- Install USB drivers for your HTC device. Check out this link.
- Enable USB debugging option on your device: Settings > Development Options > USB debugging.
- Ensure that your HTC One M8's bootloader is unlocked and that you have a recovery tool like TWRP or CWM.
- Your device must be charged to at least 80% of power.
How to update HTC One M8 to CM 12.1 Android 5.1 lollipop:
Here are the steps to help you update HTC One M8 to Android 5.1 based CM 12.1 custom firmware:
- Connect your HTC One to your computer using a USB cable and copy the ROM and GApps zip files to your phone’s SD card root folder.
- Copy / paste the boot.img file to the Android-sdk-windows\platform-tools directory.
- Disconnect the USB cord and power off your HTC device.
- Boot your device in the Bootloader mode by pressing and holding the Volume Down and Power keys.
- Once in the Fastboot mode, navigate to android-sdk-windows\platform-tools directory on your computer and open command prompt with Shift + Right-click combo and click on the Open Command Prompt.
- Type the following string into the window:
- fastboot flash boot boot.img and press Enter.
- Fastboot reboot - press Enter again.
- Follow the onscreen instructions and select Bootloader > go to Recovery.
- Once in recovery, perform wipe data task: from CWM recovery menu, select wipe data / factory reset and confirm the process.
- Also perform wipe cache partition followed by wipe dalvik cache (from Advanced).
- From recovery main menu, select install zip from sdcard followed by choose zip from sdcard. Locate the CM 12.1 Android 5.1 custom firmware file and confirm the flashing process.
- Once the ROM is flashed successfully, repeat the above step but select GApps package this time.
- Return back to main recovery menu and reboot your HTC One M8 into the new custom ROM. First boot takes a good 5 minutes so please be patient.
Enjoy the new ROM with fresh looks of Lollipop.