A button is not an actionable device. That is, you don’t turn it on and off by using the app, for example. it doesn’t really have a state like that. . When it is physically pressed, it sends a message to the hub, which then can trigger other events.
So you would do this in a different way than you were imagining. Echo doesn’t have to know the Samsung button even exists.
instead, it would work like this.
-
you physically press the button
-
the button sends a message to the hub, which then uses the official smartlighting feature to turn on a virtual switch which is also a sensor ( more on that below)
-
when the virtual switch turns on, the virtual sensor is changed to “open“
-
echo recognizes that the virtual sensor opened and triggers the echo routine (not a SmartThings routine) to turn on the Echo compatible, Smartthings incompatible device.
See the community FAQ on how to create the virtual sensor and use it in this fashion:
End result: pressing the Samsung button causes the other device to turn on. 
Oh, and the FAQ will take you to a list of steps to follow to get the virtual sensor set up. Make sure you follow them exactly in the order given or you will be able to see the device in your echo app but it will not trigger the echo routine.