An official build of CyanogenMod 13 featuring Android Marshmallow is now available for the Galaxy Note 3. Based on the latest source of CyanogenMod, the custom build is rooted with Chainfire's SuperSU and a deodexed version of firmware.

XDA member Morningstar, the developer of the ROM, says although the CM13 build is stable, since it is still going through an experimental stage, it has several issues. The developer notes that call, message and mobile data do not work as the SIM card is not recognised, but the issue seems not related to the CM. If you want to make calls with this CM ROM, use Hangouts.

Apart from these, the external SD card does not work after formatting the stock CM file manager; Bluetooth and capacitive key backlight settings also do not work. The developer asserts that these will be fixed in due course.

In case you still want to try out this ROM, following is a guide for a step-by-step installation process. The CM13 build works with the Snapdragon powered Note 3 models which are N9005 or N9002. Do not use this on any other model. Also, you need TWRP recovery to install this custom firmware. Most importantly, do not forget to create a backup of all data of your phone.

Download files

CyanogenMod 13 ROM

Gapps

Gapps fix

How to update Galaxy Note 3 to Android 6.0 Marshmallow via unofficial CyanogenMod 13 ROM

Step 1: Copy the downloaded files to the phone's storage and remember the location. Unplug the phone from the computer

Step 2: Boot the Note 3 into recovery mode. You might use the Quick Boot app from the Play Store to place the phone into recovery mode. Just download and install the app on your phone. Then launch it and follow the on-screen prompts to boot into recovery. Alternatively, use the following hardware key combinations:

Switch off the phone and wait for the device to go off completely

Press the Volume Up, Home and Power buttons together

Step 3: In recovery mode, create a Nandroid backup of all data of the phone. From recovery mode menu select Backup, then do a swipe on the bottom of the screen to confirm the process

Step 4: Once the backup is complete, perform a full data wipe. Select Wipe, then Advanced wipe, and then select Dalvik Cache, System, Data and Cache. Now do a swipe on Swipe to wipe option

Step 5: Return to the recovery menu and tap Install; then install the folder where you have saved the CM13 ROM; tap on it and do a swipe on the Swipe to confirm flash option

Step 6: Once the ROM is installed, repeat the process to flash Gapps and the fix also

Step 7: After the installation process is completed, select Reboot system to restart the phone

Wait for about 5-10 minutes to boot the phone. It might boot into a black screen with status bar only. Wait for a few minutes until the ROM starts setting up wizard and work normally. Head over to the XDA development thread to know more about the beta CM13 ROM.