I have zero relevant experience so please take my advice with a huge grain of salt. But here it is anyway …
[ul]
[] Don’t underestimate the importance of inspiration and motivation. Helping your stepson acquire the internal drive and the love of learning will pay off a hundred fold. The knowledge and skill acquisition will follow. The inspiration can come from you, teachers, or a tutor.
[] After a few months of your stepson getting some better instruction you’ll be in a better place to really assess his strengths and weaknesses and his potential. You’ll also be able to tell which of his interests seem to really enduring ones. You can then better pinpoint the specific areas that play to his strengths - it’s always easier to put a round peg into a round hole rather than a square one.
[li] No matter what, it’ll be tough to make up for many years of lost ground in just one year. If your stepson has the potential but lacks the proper foundation and the time to fix it, perhaps you could look into a 13th year program (if it’s financial feasible and after you’ve researched the pros and cons)?[/li][/ul]
Also, JHS’s post where she/he talks about other options (e.g. community college, gap-year, 5 year engineering plan) that might be worth considering seems very good to me.