Where is the best place for him to start from absolute scratch? What resources can we point him to? Who can help?
https://learnxinyminutes.com/docs/python3/ (Python3)
https://learnxinyminutes.com/docs/javascript/ (Javascript)
https://learnxinyminutes.com/docs/git/ (Git)
https://learnxinyminutes.com/docs/markdown/ (Markdown)
Read the docs. Read the source. Write docstrings. Write automated tests: that's the other half of the code.
Keep a journal of your knowledge as e.g. Markdown or ReStructuredText; regularly pull the good ones from bookmarks and history into an outline.
I keep a tools reference doc with links to Wikipedia, Homepage, Source, Docs: https://wrdrd.github.io/docs/tools/
And a single-page log of my comments: https://westurner.github.io/hnlog/
> To get a job, "Coding Interview University": https://github.com/jwasham/coding-interview-university