[ZenFone 2 Q&A, Help & Troubleshooting] vivix:
I. Before You Begin Doing Anything

**As with all of these types of tutorials, this may void the warranty of your device.

Do it at your own risk.

**Download and install the Asus USB Drivers on your PC, if you haven’t done so yet.

**This should only work on a Windows based PC only.

II. Downloading Required Files

** Necessary tools and Drivers - Mediafire Folder

**Latest OTA form ASUS website : WW_2.17.40.12

** Boot.img, Droidboot.img and Recovery.img from this MEGA Drive posted by Chinaphonearena user and belong to Shakalaca.

** System.img - if you want your phone ROOTed on latest ASUS ZF2 Firmware.

III. Yeah! Im ready to do it

**Plug in your device to your PC using a USB cable.

**Boot your device to fastboot mode Power + Vol Up to enter Bootloader Mode

**Hold down Shift and Right-Click anywhere in Fastboot Folder on your PC and select Open command here. It will launch a Command Prompt Window for you to issue commands to your device.

**When it launches, type in the following command and press Enter (.img files has to be in same folder as fastboot tools):

fastboot flash recovery recovery.img

fastboot flash boot boot.img

fastboot flash fastboot droidboot.img - droidboot.img is fastboot, and if you somehow will flash corrupted image, you won't be able to boot to fastboot anymore. Thanks to sorg

fastboot flash system system.img - Only if you use Pre-ROOTed system image from MEGA Drive.

IV. Ready to go with OTA!

** Upload WW_2.17.40.12 or latest Firmware OTA ( Full firmware ) file to phone storage (Phone storage/File.zip)

** After uploading .zip OTA file to phone storage, unplug USB cable from phone. You will recieve notification that new OTA UPDATE is avaliable for installation.

When you bought CN version of ZF2 you may have to Rename OTA file from UL-Z00A-WW-2.17.40.12-user.zip to UL-Z00A-CN-2.17.40.12-user.zip to get notification about update avaliable.

** Wait till update will finish (approx 10 - 15 min) . Phone will restart when finished. First boot may take longer.

V. Dam! No Notification!? what now...

** Boot your device to fastboot mode Power + Vol Up to enter Bootloader Mode

** At Bootloader press Vol Up to choose Recovery Mode

** You will see an error message of updating ota. Wait 5 sec and then press Power + Vol Up simultaneously until you see recovery menu.

** Using Vol Down + Vol Up choose ADB mode and connect your phone to PC via USB cable

** You need Fastboot version 1.0.32 and up to make ADB Sideload working properly with Zenfone 2

** Extract Fastboot.zip somewhere at your PC and put OTA update file ( .zip) in same folder as Fastboot.

** Hold down Shift and Right-Click anywhere in Fastboot Folder on your PC and select Open command here. It will launch a Command Prompt Window for you to issue commands to your device.

** Use command : adb sideload filename.zip

** At 100% it will go back to Recovery Mode main menu. Restart your phone.

** Done !

** Hit THANKS button and RATE this thread for 5 STARS !​

Credits to : Chinaphonearena for posting a link to latest pre-rooted system images.

Credits to : Shakalaca for making it all possible

Remember ! You should only do this at your own responsibility.

Please note !

If you posting somwhere else my guide. Please give me a Credit or just link to this thread. Thanks​

Please read all pages if you have a issue with guide. I believe other people had it as well and its already solved.​