ASUS has updated ZenFone 3.0 Deluxe (ZS550KL) to Android 8.0 Oreo. The FOTA update with build number 80.20.96.89 starts getting on ZenFone 3 Deluxe 5.5-inch variant. Also, if you have issue installing the update through FOTA, you can download and install the Android 8.0 Oreo update manually on ZenFone 3 Deluxe. ASUS has made available Oreo full firmware for download, which weighs around 1.9GB.
Android 8.0 Oreo update will improve overall performance of the ZenFone 3.0 Deluxe. In addition, the update removes many third-party apps from the device, such as TripAdivisor, Puffin Browser, Kindle, Do It Later, Mini Movie, Quick Memoand, and PhotoCollage. The update also removes several default apps.
If you would like to install the Android 8.0 Oreo update on your ZenFone 3.0 Deluxe (ZS550KL) manually, then here is how to download the full firmware (build WW_V80.20.96.89) and install manually.
Keep in mind that you should download correct firmware build for your SKU. Check the SKU by going to phone Settings > About > software information > Build number and see the software version for WW, CN, JP, etc.
Manual Firmware Installation Instruction for ZenFone 3 Deluxe
1. Download WW_V80.20.96.89 update zip file for ZS550KL from here (1.9GB).
2. Double click the firmware zip file to see another zip file it.
3. If another zip file found, unzip the downloaded firmware zip file
4. Transfer the firmware zip file to the root directory of your phone’s internal storage.
5. Disconnect your phone from PC. You will see firmware update notification popped up on status bar.
6. Select it and follow steps to update firmware.
After completing the installation, your ZenFone 3.0 Deluxe will reboot into the Android 8.0 Oreo. Enjoy! Need any help? Ask it in the comment below. (Source)