You can update your GridION via the command-line or through the GUI within MinKNOW.
To update via MinKNOW simply navigate to the Host settings, then select Software.
Here you will see buttons to update the software, if available.
To update via the command-line launch the Terminal app and type the following two commands one after the other.
sudo apt update
sudo apt install ont-gridion-release
If prompted to provide the password for sudo permissions, this can be found in the quick install guide provided with the GridION when it was shipped or here.
(To change the default password, please see this page).
You must power-cycle your GridION following the update for all processes to complete successfully (this will not be prompted for).