1. download adb
Code:
https://androiddatahost.com/wp-content/uploads/minimal_adb_fastboot_v1.4.2.zip
2. unpack it any place, i suggest you to move it to c/adb is quick and the best way.
3. in keyboard press windows key + r, type cmd, than press enter
4. in black cmd window you must type 'cd c:\adb'
#tips# if other disk like D first 'D:' than cd D:\adb or cd adb (or just paste your path to folder)
5. type adb devices to see : 1) correct adb work ? 2) drivers for phone work correct if not u need drivers
5b. In phone go to developer mode and select 'debug usg'
#tip# developer mode turn on if 7 times touch build version in information section.
5c. If connected click in phone 'yes' and remember connect debuggin with pc.
6. if after type adb devices you have somethink like this :
7. if good like this type 'fastboot flash recovery recoveryname.img
#question# recovery file where ? - recovery.img paste to main adb folder
8. just wait for pass and dats it :] u have custom recovery
Drivers link
Code:
http://dlcdnet.asus.com/pub/ASUS/ZenFone/ZE500CL/ASUS_Android_USB_drivers_for_Windows_20150212.zip
Check work, or search here
Code:
https://www.asus.com/Phone/ZenFone_5_A500CG/HelpDesk_Download/