it in the middle of the other 3 edges as indicated by the 3strokes
on the arrow.
all the crease in all the 4 corners has been corrected, sharp
start by pushingdown
at the point where the small arrows between the 2 A's meet.
in on the other side of the paper and hold the fold together that
forms the two triangles, as show and continue with other 3 corners.
inside and turn down the triangular lock. And complete the model.