Inserting layers into serial changes the indices of the layers (the number in the param names).
What you need to do is go through the state dict before loading it and adapt the layer indices.
For example, your first dropout layer seems to be number 3 (the fourth module). Thus the module.features.3.weight needs to be mapped to module.features.4.weight (don’t do it inplace if you use ascending order) and all subsequent layer parameters’ indices need to be increased by at least one, too.
Best regards
Thomas