Confirm it works on J120AZ firmware version J120AZTUS3AQE1
Steps:
1. Enable developer options, usb debugging and OEM unlock
2. Use Odin v3.12.7 to flash in AP tab:
ENG_BOOT_J120A_PC1.tar
3. After reboot copy
NewKingrootV5.2.0.apk in phone, enable in security install from unknown sources, install app and run, then root
4. Open Z3X, choose model, press Read Codes New
5. Flash back stock firmware:
J120AZTUS3AQE1