[ZenFone 2 General] fanfan54:
EDIT3 15/08/2018 - Some links broke. I found a better way to get the files: go to this thread (RAW firmware collection) by RealYoti here : https://xdaforums.com/zenfone2/general/z008-z00a-z00d-z00x-raw-fw-collection-t3448966

All the files are here and they will never expire

In case of problem I still have the files on my computer, maybe one day I will upload them myself on my web server :)

EDIT2 07/06/2017 - I updated links. + INFO: My ZE550ML phone bricked again, but this time with no USB logo and no vibration at boot. The only tutorial that worked for me is the one from

Tech YouTubers

channel (click to go to their YouTube channel). Please check their tutorials, in case they made a new one. Try multiple tutorials, for me only an older one worked: this one! :) (during the video tutorial, I was somehow blocked after flashing img files: black screen. But, I managed to run my own guide again, and this time it worked! The video says to flash ZE551ML xFSTK file on ZE550ML device, and flash ZE550ML xFSTK file on ZE551ML device. It allowed me to boot my device on fastboot but it prevented me to boot Android after flashing the correct ZE550ML img, so I had to flash, normally without reversing files, xFSTK ZE550ML config on my ZE550ML to make it work, then use my guide. good luck :) You can also try directly my "standard" tutorial below, or trying it after trying the Tech YouTuber's one, hoping finally you'll unbrick your device

EDIT 03/09/2016: Updated RAW links, taken from amtech.vn. and new ZIP files from ASUS.com

Hello, just after solving my problem I wrote a guide of everything I did to unbrick my ZenFone 2 ZE550ML (bricked after installing OTA update for Marshmallow Beta).

This is a "duplicate" of my last post on this thread : http://xdaforums.com/showthread.php?t=3405331

because I want to help people who are trying to unbrick their ZenFone 2 ZE550ML or ZE551ML

Here is a detailed guide of everything I did to unbrick a Marshmallow ZE550ML stuck on USB logo with lost bootloader without losing any data or setting, everything like before bricking in my case (except settings of some non-system apps, can't figure out why) :

(Note: I recommend you to charge your ZenFone for a few hours as soon as you'll get fastboot menu at step 1, so it will not shutdown... Even if it's not turning on the orange LED, it's charging :) )

(WARNING : these are the steps I had to do in order to unbrick MY phone without losing data and installing Marshmallow. For your phone some steps might be unnecessary, if you're lucky... I know this is a very long guide but I had to do this in MY case)

(The whole guide is a "modified" version of this guide by Summit007s)

Step 1. Flash basic bootloader with xFSTK Downloader to boot fastboot

I had, first, to switch to advanced startup with support for unsigned drivers (video tutorial here),

install Asus USB drivers (link to Asus USB drivers here - note: video tutorial to install drivers from inf (the inf file for the driver is Android\android_winusb.inf) (repeat for every device available : ADB Interface, Bootloader Interface, etc...) )

and IntelSocUSB driver (link to IntelSocUSB driver 1.2.0 - Note: Before finishing IntelSocUSB setup it will ask you to configure a device : you'll have to connect your ZenFone 2 using an USB cable to your computer, while it's displaying USB logo, and WAIT FOR DETECTION IN Device Manager as "Moorefield device" under "Intel Soc" section),

to flash a fastboot bootloader (link to xFSTK_ZE550ML-sal358-amtech.vn for ZE550ML / link to xFSTK_ZE551ML-sal358-amtech.vn for ZE551ML) using xFSTK Downloader (link to xFSTK Downloader 1.7.0)

(guides for everything in this step 1: english version - same in vietnamese with screenshots and valid links - detailed PDF for xFSTK with screenshots). => phone boots on fastboot

Step 2. Flash a lollipop ROM (or Marshmallow raw image from the raw fw collection but I did not test it) with Asus Flash Tool to repair fastboot info (like serial number) and access recovery if you want to install Marshmallow from a zip

In order to get a working recovery menu (because I found a zip for Marshmallow but no raw, I'll have to install a recovery),

I had to install Asus Flash Tool (NEW link to Asus Flash Tool 1.0.0.45),

UPDATE Some links broke so I suggest you to download the raw firmware from this thread: https://xdaforums.com/zenfone2/general/z008-z00a-z00d-z00x-raw-fw-collection-t3448966, there are Marshmallow raw firmware so you can skip step 3. I havent tried myself for now.

flash a raw file (go download it from the raw collection) on ZenFone 2 ZE550ML using Asus Flash Tool (Model: ZE550ML - wipe data : no)

OR FOR A ZE551ML flash a raw file (NEW link to WW_ZE551ML_2.20.40.184_20160504.raw) on ZenFone 2 ZE551ML using Asus Flash Tool (Model: ZE551ML - wipe data : no)

(guides for everything in this step 2: english version - same in vietnamese with screenshots and valid links)

BUT because Asus Flash Tool will wipe everything except user data and change your serial number from 0123456789ABCDEF to your legit serial number, flashing will NOT work and process will be ENDLESS because serial number has changed so phone is not found and you're not warned of that by Asus Flash Tool.

After 20 minutes of "OKAY" status displayed in green text on your phone, after 20 minutes of "a500cgfastboot.exe" running in task manager,

I think you can safely unplug USB cable, abort Asus Flash Tool by closing this software, killing "a500cgfastboot.exe",

don't restart the phone, just plug it back to your computer and reopen ASUS FLASH TOOL (notice serial number change in ASUS FLASH TOOL) and flash again with same settings but the new serial number (different from 0123456789ABCDEF).

This flash should work, after an hour or less you'll see in Asus Flash Tool that it's finished.

If it did not work, then you can reboot the phone and try again

Step 3. Flash Marshmallow zip with adb sideload, if you didn't installed it with a raw at step 2

Finally, you'll have to shut down your phone,

boot in recovery mode (guide is here),

connect it to computer, select "apply update from adb",

install adb (link to ADB Installer 1.4.3 - Note: install it system-wide but don't install Android USB drivers) on your computer,

download zip OTA for Marshmallow (NEWEST official link to UL-Z008-WW-4.21.40.191-user.zip for ZE550ML / NEWEST official link to UL-Z00A-WW-4.21.40.223-user.zip for ZE551ML),

open a command prompt in the folder where you downloaded files (using "File > Open command prompt > Open command prompt" in the Windows Explorer's ribbon), then type :

adb devices

to verify that your phone is detected (you should see your serial number in cmd),

then type the following command to flash Marshmallow stock (zip is NOT pre-rooted if you want to root you'll have to do it after) :

ZE550ML

adb sideload UL-Z008-WW-4.21.40.191-user.zip

ZE551ML

adb sideload UL-Z00A-WW-4.21.40.223-user.zip

It may take a while decompressing then sending to phone. Then select "wipe cache partition" in your recovery menu,

wait until you see again the menu (so, wait until end of wiping cache), and select "reboot").

If you want more details for each step, just ask in the comments! Don't forget to read the other guides linked in the steps (for example, the one for xFSTK)

Now pray, and your device SHOULD magically boot the latest beautiful stock Marshmallow ROM from Asus, with all your data (except, maybe, settings of some non-system apps), exactly like before you bricked it.

It worked for me, but with the right new files it should work perfectly for you...

I hope you'll appreciate this "googling" work :p