… but only once.
I got a refurbed Amp today, and out of the box it was running 57.5-87010, which is a newer S1 than the current S1 version (which is 57.21-51190).
Once I added it to my S1 system, the app “updated” it back to 57.21 like all my other S1 gear.
So it IS possible to go backwards, if the app lets you.