def alignment_params(screen):
    """
    Takes a camera screen dictionary as input. Locates all scaffold intersections
    and calculates their alignment parameter (distance from left edge * distance
    from top edge).
    
    Returns the sum of the alignment parameters and an updated screen showing their positions.
    """
    
    intersections = []
    alignment_param = 0
    
    
    moves = {0:(0,1), 1: (0,-1), 2: (1, 0), 3: (-1, 0)}
    
    for tile in screen:
        intersect = True
        pos_x, pos_y = tile
        
        if screen[tile] == 35:
            for i in range(4):
                dx, dy = moves[i]
                test_pos = (pos_x + dx, pos_y + dy)
                if test_pos not in screen or screen[test_pos] != 35:
                    intersect = False
                    break
        
            if intersect:
                intersections.append(tile)
                alignment_param += pos_x * pos_y
    
    for tile in intersections:
        screen[tile] = 48
        
    return screen, alignment_param