Remove the main board, flip it over, and carefully lay it on a clean work surface, so the APU is facing up.

Don't press the board against your work surface, or you may damage fragile components.

During reassembly:

Make sure all cables that connect to the board are out of the way so they don't get trapped underneath.

Carefully flip the board over so the APU is on the bottom, making sure no liquid metal spills.

Keep the board level and lower it into place.