Unscrew the two black J1 screws shown in the pic

Simply lift up the board, see the second picture

Be careful not to loose the bluetooth discovery button from the main plastic base underneath; it's missing in my second picture

Forgot to snap a picture of the grey button, sorry :-)

Reassemblig be careful and check that the on-off switch showed with circle in the third picture is in the right place before proceeding with reassembly