Lift carefully the top plate and turn it so you can see the back of the top plate.

Locate the power button behind the top plate.

Then remove the 3 screws securing the power button using a Philips #1 head screwdriver.

3 Philips #1 8 mm screws

Warning: the button has two parts that are not attached together, the top of the power button may fall, careful to not lost it (see 3rd picture).