Updating My Phone

[Joost]

Hi, I am currently the owner of the Asus Zenfone 4 Selfie ZD553KL. Recently I discovered that I can install android version 9 on my phone (currently i have android version 7). But whatever I tried, I could not install the latest android version. I installed the zip file from the official site. I might be possible I tried in the past to unlock the bootloader, but that did not worked. I think this is the issue. I tried several ways to install the zip file, like being in the boot menu, whith fastboot and my pc etc. Does anyone knows a way how to install the latest android version? Cause android version 7 just is not good enough for me.

[Christine_ASUS]

Hi Joost 
Thank you for your asking.
First, cross-Android update requires the last version of previous Android, e,g. Update to the latest Android 7 version before update to Android 8.
Second, cross-Android update can only update to the next Android, e,g. Android 7 to Android 8; Android 8 to Android 9.
Third, please note that ZD553KL provides Android 8 and Android 9 AOSP Beta version. you may evaluate which Android design do you prefer the most.
Last, please read the firmware description under the download spot carefully before you perform any update/downgrade steps. Any mistake may cause device crash or system death permanently.