The reason I asked, is becaus it looks liked you warped the flap on both sides.
Not only that, from the picture it looks like the new foam is wraped around the edge of the flap. I believe it create friction between the flap and the box, so the flap cannot move.
I whould give it another chance (after thanksgiving :chicken
.
Try to reform the flap again. I will post a pic of the foam I used.
You can get it at Home Depot.