I don't know about the S, but on the X you can pop off a little plastic cover on the front lower right of the car in the black plastic area and access a couple of red ribbons. Pulling them down in the proper sequence will open the frunk. The little cover is used to hide the towbar attachment point, so you can find it in your Owner's Manual. On my car the two red pulls were tucked up out of the way, but this is clearly their intended purpose.