Gently lift the back cover away from the phone. Do not worry if the buttons fall out, you can easily put them back later.

In order to remove the logic board, start disconnecting any cable from the board.

Be careful: the ribbon cables are fragile. Do not hurry. You need to remove every single one in order to be able to lift the board out. Start with the big, black camera connector, as the camera is not mounted on the logic board, but on the shielding underneath it.