First connect to the chargers MyINCH interface. Please check this article on how to connect to the charger: Connecting to INCH and INCH Duo directly with PC
Once connected to the MyINCH interface, open the navigation menu in the top left corner and select “Diagnostics” sub-menu:
Next, select the option “Upgrade firmware”:
And select the appropriate file (please note, always first install the system file and only then the application file):
Click “Save” and wait for the charger to reboot.
You can check what firmware is installed on the bottom of the Diagnostics menu: