Reading through the steps you say you took I think you may have missed something.
The steps (from the release notes here) are...
Consoles running ZerOS 7.8.3 or later.
To perform the update:
- Download the software from the Zero 88 website ( zero88.com/zeros )
- Unzip the download and save the .exe file onto a USB stick (don’t put it inside any folders)
- Plug the USB stick into your console - Press SETUP to enter the console’s setup screen and choose “Load” on the monitor
- Select the file from the list displayed on screen and follow the onscreen instructions
- Once the update is complete, remove the USB Memory Stick and reboot the desk