Remove the two bronze screws from the metal plate with a medium Phillips head screwdriver.
The screws are marked on the diagram.
Carefully lift the metal plate up to expose the motherboard.
There is a wire strip running through the metal plate that is soldered to motherboard and power supply board. The plate cannot be completely removed. Do NOT force plate upwards. All the ribbon cables can be safely unplugged by simply pulling them out of their slots.