[weejaya]

If the bootloader is not updated, you can push the oreo firmware zip file via adb. Mostly bootloader might have been updated during pie update - in that case, you can't downgrade. If the firmware says beta, you may be able to downgrade.

Pie update via OTA, supposed to be official, is there anyway to check the bootloader?where can i get the Oreo zip file?
many thanks

Check this thread.
https://forum.xda-developers.com/android...e-t3737186
This has some info on how to downgrade OS. Most likely you can't downgrade bootloader as Oreo and Pie updates have locked bootloaders. This may brick the mibox so I won't recommend.
What you can safely try is get the oreo firmware from the mediafire link in the above xda thread and try to update it via usb in bootloader mode. Instructions are in that thread. If it takes, it means same bootloader - you are good. If it is not, then no way to downgrade unless you find some hardware hack to downgrade.

Ok thanks Bro