I have exactly the same problem. Bricked MDZ-22-AB after update. Flashed with the Xiaomi_Mi_Box_S_MDZ-22-AB_oneday_r363.img 8.1 android. Remote workef fine, it had to be paired within ~20cm from the device. Bluetooth does work. WiFi does not work, 02:00:00:00:00:00 Mac Address, and WiFi cannot be turned on.
Grandman: As I understand, upgrading in this situation to 9 didn't help, right ?
Have you tried any USB Ethernet/WiFi adapters ?
Any ideas, what can be done/tried next ?
Maybe flashing directly to android 9 using this procedure
would be an idea ?