How to turn a game object into an instance of prefab?

Say I made 10 buttons that look the same but do different things. Then I realized I should make a button prefab, so I made a prefab from one of the buttons and stripped the event handlers to keep it general.

Now I have 10 game objects that should be instances of this prefab, but are not. I don’t want to delete all of them and make 10 instances and start over. Is there a better way to do this?

BTW I am required to use unity 5.4.1f1.

If they started off as that prefab, clicking “Revert” in the inspector view with your button selected in the heirarchy should do the trick.

If you want to add components from the prefab without removing ones that are not on the prefab, you will A) need seperate prefabs or B) use “copy component” and “paste component as new” on all the conflicting cases