Problem with upgrading Roadhog 4!

Hello Guy's

I have a problem with upgrading my system.

I hope you guys can help me out.

I have version 3.0.1. and i have downloaded the file 3.3.1. upgrade.

When i put in the usb and start the upgrade he says that : In oder in perform this software upgrade a full image is required.

Actually i really don't know what the console means with full image. i hope you guys can help me!

Greetings from the netherlands,
Mike