An electronic device includes a chassis, a rotatable door, and a latch member. An opening is defined in the chassis. A first flange extends from an edge of the opening. A first mounting slot is defined in the first flange. The rotatable door is rotatable between a closed position and an open position. The rotatable door includes a second flange with a second mounting slot defined therein. The latch module includes a latch piece with a mounting hole defined therein and a slidable pin securely engaged in the mounting hole. The latch piece is movable between a locked position where the latch piece is engaged into the first mounting slot and the second mounting slot, and an unlocked position where the latch piece is disengaged from the first mounting slot and the second mounting slot.