Remove the four silver Phillips screws attaching the logic board to the outer case.

To remove the logic board, you must first de-solder the leads of both microphones from the logic board. When soldering on a circuit board, be sure not to heat up the connection excessively.

Use a pair of tweezers to gently pull each lead as you heat up the joint with the tip of a soldering iron.

Repeat this process to remove all four microphone leads. Their locations are boxed in orange on the first picture.