I have a Zenfone 5Z (older one from 2018) ZS620KL and it started randomly bootlooping last week while in my pocket. I have never modded it and it was always in Stock ROM. I am not sure how to recover it as I have a lot of data on it still. I need any help I can get on this as I cannot format it at all.
According to what you described, I would suggest you bring back your phone to our service center for further confirmation.
The following is the contact information: https://www.asus.com/support/service-center-location
Also you can contact the local service center for help.
The following is the contact information: https://www.asus.com/support/CallUs#
Sorry for any inconvenience it may be caused.
I gave the phone to the technical service. But they said they can't upgrade to android 9. They said no phone allowed. Do I have to use beta 10 version? Official software is android 9 but they force to use beta 10 version