Can't update firmware on a C5235i

[carlsson]

My old C5235i was having a lot of printing issues, so I got hold of another one that prints beautifully. But it doesn't have the Airprint option so I want to update the firmware. However, I get an error when trying to do that.
Management Settings > License/Other > Register/Update Software > New Firmware will give an error that reads "Applicable firmware is not registered".

I *think* (it's difficult to find out) I currently have version 3.0.4.20. Can that be correct?

How can I update the firmware? Any ideas?

[ADV COPIER]

Try update via CDS

[carlsson]

Try update via CDS

Thanks. I don't really know what that is though? 🤔
If it stands for "Centralized Device Services" that means I must have an account with Canon, am I right (which I don't)?

[zoraldinho]

Service mode>Updater