EDIT: this post was supposed to be sent to the Max Pro community. Handle as such, and move it over if possible.
Model Name: Zenfone Max Pro M2 ZB631KL
Firmware Version: Android 8.1.0, OPM1.WW_Phone-15.2016.1811.165-20181205
Rooted or not: not
Frequency of Occurrence: every time I try to update the firmware
To update the firmware, I downloaded "UL-ASUS_X01BD-WW-16.2017.2005.092-user.zip" from the product page and placed into the root of the Internal Storage. The phone detects it as it should, I click on the notification and proceed. To avoid complications, the device has no PIN/password/pattern/fingerprint/face lock, secure start-up is disabled, and it is connected to the charger during the whole time. The process completes in about 5 minutes, but once I'm back in Android, a message is displayed:
"System update failed (3)
System restored to previous configuration"
Nothing more. And really, in the Settings, every version number remains the same. I tried it twice and it fails the same way.
There are several posts on this forum with the same error, but you never really gave a solution, only "please send more info", "check your PM" and wink-wink smileys. Will you share information that will actually solve this problem?