[ROM][Full Firmware] ASUS ZenFone 2 ZE551ML Marshmallow WW-4.21.40.223

How to OTA update ? (Go to settings>About>System Update>Check for Update)
How to update Manual ? Place to Internal Storage>Restart>Click Update
How to update via ADB sideload ? Here 

ZENFONE 2 ZE551ML firmware: 

WW VERSION
WW-4.21.40.223

Description

ASUS ZenFone 2=ZE551ML(Z00AD/Z00ADA/Z00ADB/Z00ADC) software Image: V4.21.40.223 for WW SKU only* (andriod M) Improvement Item: 1)Improve Wi-Fi/Bluetooth stability   2)Update Security patch 3)Improve system stability  4)Support India SOS call (India only) Steps of Update:  1.Check software version of your device** 2.Download device software and Update SOP (From “Manual” Item) 3.Only apply to same SKU update, Example: WW->WW, CN->CN, . 4.Software update cannot transfer the software SKU and downgrade the software version. 5.Wrong SKU may cause update failure, please update the same SKU version only. *How to know the device model?  Path: Settings->About-> Model number Example: ASUS_T00I **How to know the device software version?  Path: Settings->About-> software information->Build number ***System upgrade may cause part of data missing, please buckup your important data before system upgrading.

File Size	1.18 GB                                                2017.01.10  update
Download from	Global