There is some great news for the Asus Zenfone 2 ZE551ML and Asus Zenfone 2 ZE550ML users as both of these smartphones have finally received the Android Marshmallow update after much waiting. Both of these devices were released back in March 2015. The Zenfone 2 Laser ZE500KL and Zenfone Max ZC550KL from the 2015 Zenfone series have already received the Marshmallow update.
Asus has started rolling out the Android 6.0 Marshmallow update over-the-air for these two devices and you should get the notification for the OTA update anytime soon. The update weighs 1.1GB, so we would suggest you download it over Wi-Fi or some other stable network.
The Marshmallow update will bring a host of new features to the Asus Zenfone 2 ZE551ML and Asus Zenfone 2 ZE550ML including Google Now on Tap, Doze mode, customized app permissions and many more new features.
If the OTA hasn’t reached you, you should check it manually by navigating to Settings > About phone > System updates > Check For Update. If you don’t receive the OTA update even then, you can download the update package and flash it manually by following the instructions given in the below source link. However, if you are unfamiliar with the process, we would suggest waiting a little bit more for the OTA update.