Brilliant find, I made the same mistake when quickly trying to confirm.
It doesn’t help that in German the two buttons are labelled “Aktualisierung” and “Aktualisieren” … basically the same thing, the first is the noun and the second is the verb for it. 
So, people reading along can learn from our mistake:
If you want to mess with the Testing menu, set your phone to English first.
Mobile network reception is ok?