>>624935
>>624936
>>624937
>>624938
A bit late, but pic related might help a bit.
First, squash the top part using creases of step 40; the bottom part of the model won't stay flat.
Then, use the existing crease marks shown (not very clearly) in step 41 to flatten the model again.
Pic related shows what creases to use, and bottom right part is a bottom biew of the model.