There are some issues in your code:

in VAE.forward you are not passing x to self.VAE1, so that x will be the submodule not its output
I would suggest to save and load the state_dict instead of the complete model as described in the Serialization docs 11

if you would like to remove the last layer from VAE1, you could e.g. replace it with an nn.Identity layer
to freeze the base model’s parameters, set their requires_grad flag to False as described in the Finetuning tutorial 23