How to install Android 6.0 Marshmallow KDZ on LG G3 D855 [Guide]

LG-G3Unlike most other Android devices with the CM13 custom ROM available, the LG G3 smartphone with the model number D855 has the official Android 6.0 Marshmallow already released as an over the air update. However, there are still many people who cannot accept that update, or just haven’t yet found that OTA notification arriving to their device’s notification panels.

For all of you folks, there is this official stock ROM based on Android 6.0 Marshmallow you can install via the flash tool to get your device running on the Marshmallow update.


  • The following guide installs the official Android 6.0 Marshmallow software update on the LG G3 only. Do not follow this guide and flash the same file on any other device as it will likely brick the device.
  • Moreover, it needs to have the D855 model number. You can find out your model number by pointing to the Menu > Settings > About Device > Model Number.


  • You’ll need to have the Developer Options unlocked and the USB Debugging Mode enabled. You can unlock the Developer Options by pointing to the Menu > Settings > About Device > tap the build number seven times.
  • Now that everyone has the Developer Options menu unlocked, you can enter the same and enable the USB Debugging Mode. You’ll find that available from the Menu > Settings > Developer Options > USB Debugging Mode. Just check the box, leave the menu and it will remember your settings.
  • Those of you coming here using a custom ROM and not the stock ROM must back up the data before continuing. You will wipe the data during this guide and should backup before continuing to ensure you can restore that data later.


  1. Download the Flash tool to your computer from here.
  2. Download the Android 6.0 KDZ firmware from this link.
  3. Download the aforementioned files from above to the computer and shift them over to the desktop.
  4. Right-click over the files and choose the “extract here” option to have those files available.
  5. Transfer the KDZ file over to the same folder as your LG Flash Tool.
  6. Upload the KDZ file to the Flash Tool.
  7. Long-press the Power button on your G3 and turn off the device.
  8. Reboot the G3 up in bootloader mode by pressing the Power and Volume Up keys for around 8 seconds and then connect the USB cable to the computer and the device before letting go of the keys.
  9. Run the Flash Tool so the user-interface opens on the computer.
  10. Choose ‘CMDA’ from the menu.
  11. Choose ‘CS_EMERGENCY’ for the¬†PhoneMode.
  12. Click the folder icon and load your KDZ 6.0 firmware file.
  13. Those of you running a custom ROM should choose the CSE Flash; choose Normal Flash if you are running a stock ROM.
  14. Click the Start button.
  15. Wait until your new 6.0 ROM is flashed on the LG G3 device before eventually unplugging from the computer and rebooting your device manually.

Once the LG G3 reboots, you will have the latest Android 6.0 Marshmallow stock ROM running for you to enjoy.

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