To update the firmware and the library, you need to write the files on a formatted USB stick from a good quality.

After inserting the stick into the GC28, a button appears around the firmware indication in the top right corner from the overview page.

As soon as this button is grey, you can tap it to open the USB menu. Just select the file you want to install and click update. Make sure the process is completed, otherwise just repeat the update. Restart the GC to activate the firmware and perform a reset all to activate the library.

If the button stays yellow, you can tap the button to see the reason why the USB stick isn't working.