lock button until level completed

On my UI I want to have the level selection button is locked until the object in the previous level was selected

High level overview here.

  1. Make a game instance.
  2. Put variables in this game instance.
  3. When something happens in a level, set the variable to something specific.
  4. Make a locked icon.
  5. Check the game instance to see if the button should be locked. If yes, display the locked icon and make the button un-clickable.
  6. If it should not be locked, restore the button to normal.

7. Save and load from within the game instance using either savegame or a solution on the marketplace.