This script converts the html rendering of a Jupyter Notebook back into its Jupyter Notebook form.
python html_to_ipynb.py /path/to/html/input.html /path/to/notebook/output.ipynb
This script relies on the DOM construction being equivalent to the default output from Jupyter server when notebooks are converted to html. It may or may not work with your particular file.
This script was adapted from this StackOverflow answer: https://stackoverflow.com/questions/28972614/jupyter-ipython-notebook-convert-an-html-notebook-to-ipynb