A cover assembly for a portable electronic device is described. The cover assembly has a cover comprising: two cover extensions extending substantially perpendicular from the cover. Each of the two cover extensions has an abutment towards a center. An angular spring with two wings and two upwards arcuate ends is included in the cover assembly, each of the wings forming a bias angle relative to a line between the two ends. Two housing extensions extend from a surface of the portable electronic device, each of the housing extensions has a protrusion mating the corresponding abutment, and a guide having a form substantially corresponding to the upwards arcuate end. When a force is applied to the center of the angular spring, the bias angle decreases and the upwards arcuate ends are urged upwards, thereby causing the abutments moving outwards, and unlocking the protrusions.