Asus Zenfone 3 Related Question and Answer

Unlocking the bootloader gives you an option to perform multiple modifications to your Android device but, rooting your phone void the warranty and also you won't be able to receive any OTA updates further. 

To unroot and lock your phone's bootloader you can follow the steps carefully mentioned below:

1. . Download the factory RAW ROM from the link below as per your device model number.

   
   

   ZE520KL:  Here

   ZE552KL: Here
   

   
   

2. . Unzip the files and click on install adb-setup-1.4.2.exe (You can find this in Bootloader Kit)

3. . Hold Shift and Right Click anywhere in the folder to open PowerShell window or Command Prompt Window

4. Now just copy  paste this command: fastboot devices

5. . After running the above command if it shows the serial number of your device, it means you are good to go

6. . Now copy paste this command:  fastboot oem lock

7. . Then, copy paste this command: fastbook reboot bootloader

8. . Once you are done with running above commands. Congratulation! You have locked your bootloader successfully

   You can see that on device stats or fastboot splash screen

   
   

   Now Download the Stock Oreo ROM here and flash it to your device using Asus Flash Tool 

   ZE520KL: Here  
   

   ZE552KL: Here

   
   

   While flashing RAW firmware via Asus Flash Tool if you get any error ( FRP request error) just ignore it.

   After booting, if it asks for pin then just wipe data and cache via Recovery Mode 

   To enter recovery mode just press Power Button + Volume Down)

   Also, check the attached video for your reference for Asus Zenfone 3.