The Scrap Processing map is the most complicated one you've visited yet. There are a lot of treasures to find here, but it will take quite a bit of legwork to collect them all. After backtracking from the start for a Phoenix Down, travel forward through the map, activating any devices you see. Eventually you'll come across a large structure with four platforms surrounding it. Each platform has some enemies and an activated device. Defeat all of the enemies, activating all four devices as you do, to activate the generator in the center. In addition to revealing a treasure, doing this activates a number of platforms back at the beginning of the area. Backtrack to that section and activate the newly available items to find two more treasures before moving on to the end of the chapter.