is there a reason that particular teacher can't ask him for his completed work at the end of each class period? When he gets initials, she says "where is your work?" and he goes through his stuff to get it? Then put in the 504 that he has additional time to get to the next class?
My kids are obsessed with screens and during the summer I'm looser, but during the school year they simply don't get any screen time until they get done A,B, and C (like homework, chores, etc.). Then the screens are a reward (rather than taking them away a punishment). So you could go through his stuff at home and make him scan/email any work (with you supervising) before he can do X or Y on the screens. I'm not saying take ALL screen time away before he does these things, but maybe some aspect of it, like game playing. I don't know--just a thought. It's really the only thing I can do to motivate my two. Maybe if he has to scan/email himself, at some point it will click that it's not much fun, and he will be better at remembering to turn it in.
Also, make sure you save all the emails submitting late work. You can use them as documentation that educational performance is affected. Make sure they know that YOU are helping to get the work submitted. Because otherwise they can say that if he is able to get scanned work in, there is no problem. Yes, there is, because you can't/shouldn't have to continue to do this for a 12 year old. He doesn't have the organizational skills necessary to function in certain classes up to the level of peers. Basically they are expecting YOU to do what a special ed teacher should be doing at the school.
