Updating the Naso firmware should normally be done remotely over the network using the Evoko Naso Web Admin Portal found here: https://naso.evoko.se/admin.
A firmware reset is different from a firmware update in that it resets all settings and leaves the Naso in a brand new out of the box state. After firmware resetting a Naso you will have to claim it again using Evoko Naso SetApp
Place the Evoko Naso display side down on a firm table or desk and locate the cable routing clip on the right side of the device.
Remove the cable routing clip to identify the access to the reset button.
At this point you will see a small arrow indicator on the bottom of the routing clip area.
Insert the paper clip into the hole indicated by the arrow and plug the device into power. Hold the button down for 5 seconds.
The unit will reboot and begin the onboard firmware reset process.