I'd say to try Harvard's CS50, and if he gets stuck to seek out a mentor or one of the online communities to help answer questions.
Ideally he should find someone also interested and take it together, from my experience learning hard things is significantly easier when you have someone to talk to whose also struggling.
There is a subreddit [0] for the class where the instructor (David Malan) posts frequently. Very helpful for asking questions and learning more!