Manually Update Asus ZenFone 2 ZE550ML/ ZE551ML to Marshmallow

Asus starts rolling out Android 6.0 marshmallow update to ZenFone 2 ZE550ML and ZenFone 2 ZE551ML variants. The OTA (over-the-air) update rolled out in phases, so it will take several days to get it on your device. However, if you do not want to wait for the OTA or facing network issues that prevent you installing the update, you can manually update your ASUS ZenFone 2 to Marshmallow.

In this guide, we will let you know how to update for ASUS ZenFone 2 ZE551ML and ZE550ML to Android 6.0 Marshmallow manually. The most important changes in this update are greater control over app permissions, battery consumption optimization (Doze), and performance enhancements. Also, this update discards many bloatware apps.

Before get start to update manually, check the availability of the new software by going to Settings > About phone > System updates > Check For Update. If update is found let it download and install.

If you have any issue downloading the firmware, you may follow the manual method given below.

How to update ASUS ZenFone 2 ZE551ML & ZE550ML to Android marshmallow

Disclaimer: Follow the instruction at your own risk. We will not be liable if any damage occurs to your device and/or its components.

Important: Backup all data you have on the phone before proceeding. The guide intended for technically talented users only.

1. Download Android 6.0 Marshmallow FOTA update zip file for ZenFone 2 ZE551ML (version WW-4.21.40.61 -ZE551ML/Z00A) [HERE] and ZenFone 2 ZE550ML (version WW-4.21.40.54 – ZE550ML/Z008) [HERE]

2. Copy and Paste this .zip to your phone’s internal storage

3. Software update notification will pop up on your Zenfone screen. Just tap to update.

If the above method does not helped, you may try the recovery method described below.

1. Copy and paste the downloaded firmware zip in to the SD card of the phone

2. Boot your phone into recovery mode by pressing and holding Power & Volume Up buttons after switching off the phone.

3. In recovery, select Apply update from sd card, select the firmware zip file.

4. Once the installation process finished, reboot your phone.

You can also sideload the update zip file via ADB. If you have ADB and Fastboot drivers installed on the PC, follow the below step.

1. Enable USB debugging option from Developer Options menu.

2. Rename the downloaded firmware zip file to update.zip and place it inside the ADB installation directory.

3. Boot you phone into fastboot mode. To do so, turn off the phone and press and hold Power + Volume Up buttons few seconds.

4. Select Apply update from ADB, and then connect the device to PC via a USB cable.

5. Inside the ADB folder, press Shift key, right click and select open command here.

6. Issue the below command to check your connection

adb devices

7. If your device is listed, issue below command to flash the firmware.

adb sideload update.zip

8. Wait until the process completed and then reboot the phone.

If you have any question, leave it in the comment section below (Source)