I know that Hagrid is not really the right age, but still: by the end of Chamber of Secrets, the Minister of Magic knows that Hagrid had not opened the Chamber fifty years before. Even if Fudge did not trust Dumbledore on that point, it is clear that after DH, Kingsley could well have declared Hagrid innocent of all charges, and thus allowing him to have a wand.
My question is simple: considering that Hagrid is innocent after all, could he have re-attempted Hogwarts even if he is older than 10? And in a broader way, are there any canon examples of overage wizards/witches who still attempted Hogwarts?
As implied in the last question, I'd rather have canon-based answers (Novels, Pottermore, JKR) but no Wikia.