If anyone else is still wondering what are those for, then as Adam said, black L-shaped part is a holding piece for the screw which mounts vertical stand to the console.
Silver springy metal piece is connecting ground (together with a BD Drive cover and woobly metal sheet) from power supply to internal metal parts and among them, also circuit board of Blueray Disc Drive.
Forgetting to put it back in, can be the cause of Drive not ejecting or not taking disc's anymore, but I doubt it would make console dead like not turning on, UNLESS someone forgot also/(or just - in meaning - only) that metal sheet that sits on top of Power Supply Unit and PSU long screws wouldn't have enough connection with motherboard cover plate (dirt, rust) - that would likely cause console acting strangely. In extreme cases not turning on or powering down after few seconds.