Where is power button located when disassembled?

Just bought broken ps4 pro. Missing power n eject part of chasis. Im planning on buying a new chasis but im not sure where the power button is if the top isnt on. Also whats this small motherboard on the left of console for closest to power button side for? Forgive my terminology. Could you guys please share pics of what its supposed to look like please. Ive worked on many ps4’s but not a single pro. Wont let me post pics. My instagram/twitter is @chochahair If youre willing to send pics. Or ladiesmen411@yahoo.com . Id really appreciate it