I would tell him that he has X period of time over the summer to show a willingness to work otherwise he has to go to the public school. Show him the enrollment forms, etc. so he knows you're serious. if he ends up in the public school, tell him that if he completes his work there, you can consider homeschooling again after X amount of time (like a quarter or semester). Or, if he chooses, he can stay in school. I think you need to lay it out for him and then act on it. Focusing for one day on schoolwork is not going to be good enough. He has to be serious about it for a couple weeks and demonstrate a permanent attitude change. I'm not sure how long he has been home schooled but peer pressure can do amazing things. He may end up working because it's expected, and that might change his "I can't" mindset. Not likely but I don't see what other options you have at this point. My kids with executive functioning issues can also be stubborn and resist work and it's very frustrating figuring out why and what to do about it. The key accommodation seems to be to break things down into small steps. Seeing too much work all at once is overwhelming. So even with math, you could try giving him only a few problems at a time.
