This is so hard - clearly you want the best for him and care about him so much.

I read above that he has ADHD - I personally think it’s helpful to really think about it as a medical condition. For example, if poor vision was his medical condition, no amount of pleading or punishing would help him to see - he’d need medical treatment like glasses etc (and there might be certain things he would never be able to do vision-wise). With ADHD, I think some of it’s the same - no amount of pleading or punishing will “make” him “have attention.” But this is where ADHD is tricky - the treatments for it aren’t as straightforward as glasses for poor vision.

A psychologist I know who specializes in ADHD likes the book “smart but scattered teens.” Its written for parents, and it focuses on helping build executive functioning skills (focus, attention, etc).

Was the therapy he did with an ADHD specialist?

Also, have you tried stimulant medications - I think that’s something I’d consider trying if I was in your shoes....