Clean off using a cotton bud the old Thermal paste from the fan heatsink. When replacing the fan onto the new motherboard, you will need to apply a thin layer of Thermal Paste, which may or may not have come with the replacement motherboard. Apply the paste onto both metal plates on the motherboard.
Use a pin to remove the SD card tray.
Need to also remove all 5 Motherboard Screws before lifting it off.