Zenfone 2 ZE551ML and ZE550ML Gets to Android Marshmallow Update

The two Asus Zenfone – ZE551ML & ZE550ML received the Android Marshmallow update at the end of the summer, last year. However, this update wasn’t an OTA, so many users didn’t know that they could manually update their devices. If you’re still running your smartphone on Android Lollipop, then you can download and update your smartphone to Marshmallow.

While Marshmallow added a lot of improvements in usability and system that Lollipop doesn’t have, it has been considered by others that it is also buggy and removes some features users might not like (removed stock apps, apps cannot be moved to SD card, less storage space for user files among others).

Download the OS Update File

Go to the official Asus website and download the appropriate file for either the ZE551ML variant or for the ZE550ML one. To find the exact place where the downloadable files are, go to these following links:

1. Link for ZenFone 2 (ZE551ML)
2. Link for ZenFone 2 (ZE550ML)

After that, under ‘Driver & Tools’, you will have to choose ‘Android’ as the OS, expand the ‘firmware’ section and choose the latest version (for example, for the ZE550ML variant we can see WW-4.21.40.311 version of firmware).

Update Zenfone 2 With the Downloaded File

You can update your smartphone with three methods, and the first one is the safest one to perform. Before you update your OS, we recommend you to backup all the important data, such as photos, messages, videos and so on. It’s also best to move all apps into your SD card because the Marshmallow OS will no longer let you do that.

Update With the Help of a PC – ADB

This method will assure you that you will not brick your phone while you update it. You will need to use a PC for this method.

1. Download and install to your PC the following: ADB & Drivers
2. Turn off your Zenfone 2.
3. Perform fast booting on your smartphone: press and hold ‘Power’ and ‘Volume Up’ buttons.
4. Using volume keys, navigate to ‘Recovery Mode’. Select by pressing the power key.
5. Select ‘Apply Update from ADB’ in the ‘Recover Mode’ and use a USB cable to connect your smartphone to the PC.
6. On your PC go to where you have saved the file with the Marshmallow update, right click it while you press ‘Shift’ key and select ‘Open command window here’.
7. Run this command in the command window: Replace UL-Z00A-WW-4.21.40.184-user.zip with the name of the file that you have downloaded. For example, for Zenfone 2 ZE550ML, you will write this: adb sideload UL-Z00A-WW-4.21.40.311-user.zip
8. After this, the file will be sent to the phone and the installation will begin.
9. After it’s all done, you can choose ‘Reboot system now’ and then you will have to wait a bit more for optimizations of apps.

If you don’t have access to a PC, you could try performing the update with the help of a SD Card or within Android.

Updating from Android

For this method, you must have 60% battery at least, so that your phone will not turn off while the installation takes place. You must also have at least 2 GB free internal space.

1. Go to ‘Settings’ -> ‘About’ -> ‘System update’.
2. Copy the file that you have downloaded in the internal storage.
3. Your smartphone will show you after a few minutes that it has detected a System Update File. Tap on that notification.
4. Select the file and begin the update.
5. The phone will first reboot in recovery mode, it will update and the reboot. After that, it will take some time to optimize its apps, so let it finish the whole process.

Updating via SD Card

1. Copy the Marshmallow file that you have downloaded for your Zenfone 2 and move it to the SD Card that it’s in your smartphone.
2. Follow steps 3. And 4. from the PC method.
3. Here you must select ‘Apply update from SD card’.
4. Reboot the system – ‘Reboot system now’ – and wait for the apps to be fully optimized.

If you don’t like the way your new OS looks like or its performance, you can downgrade back to Lollypop.