The firmware can be checked and updated in the enviolo app. You need to connect with the enviolo app first. 

Explanation

If you want to know how to connect to the enviolo app we refer you to this article:

How to connect with the enviolo app?

Update enviolo firmware

To update the enviolo firmware make sure to connect the enviolo app on your phone with the interface that you want to update. If there is an update available the app should give you a notification when you start the app. Click on update and the app will load the newest firmware onto your device. You can also go to settings and click on the "Firmware" button just below the start-after-stop slider.