An update...
So, he insisted on going back shortly after we pulled him (mid April) and has been miserable ever since. Self sabotaging and basically not doing any homework. We kept insisting that he go with the goal of finishing out the year but now have pulled him (only a week and a half or so to go).
I look back now and think why? Why so much pressure and stress? Daily cajoling and punishing. Thinking back years - he has been unhappy for so long.
We've decided to go with a self directed learning program via an independent distributed learning school mixed with electives at our local B&M.
I'm so relieved that the daily struggle to get him to go is over and that we have a hopefully good solution moving forward.
He seems happy with the solution. Exhale.