He should get the 504 or IEP plan now.
Of course he’s not into school if he’s not getting accommodations that would help him. It’s demoralizing to be asked to perform academically in ways that you have no hope of doing well at without accommodations. What does he need? Extra time? Copy of class notes? Ability to extend deadlines? Scratch paper? Ability to take pics of whiteboards in class (even when phones aren’t allowed? Testing in a small quiet environment? Use of a calculator? The ability to use spell check and speech to text and writing organizers?
My ADHD kid had all of that. Cannot imagine him being “into school” without it!