This is what I have found works with my 12-year-old captain literal - I define things in black and white - right and wrong. What you did was wrong because you deceived people into thinking you could do something when it wasn't really your effort. Cheating is wrong because it keeps us from actually learning the skills we need and it causes other people to not trust us when they find out we are willing to deceive them to get what you want. He is likely to understand this because it is about his own actions and the consequences to himself because of those actions. When we want our very literal children to "care" in the sense that we define caring, I think we just confuse them and get ourselves hurt because we think maybe they really don't care. They do - they just process things a lot differently.
This past week, my son finished his part of a group presentation and then started a game of "air basketball" with the other kids in his group who had finished. When I spoke to my son about it, he was more amused than upset. It was after he'd finished his "job" and wasn't that big of a deal. I then asked him if some part of his brain told him it was wrong, he said that, yes, that was true. So I asked him what was more important than listening to that part of his brain. He was honest - having fun. So then I explained that once his teachers and his parents understood that he would choose fun over not doing what was right, we couldn't trust him. He wouldn't be allowed to drive when he was 15, because what if fun was racing another car instead of following the rules of the road, etc. It was only at that point that it seemed to click. He said he had no idea why it was such a big deal but now he could.
With my daughter, I was able to talk about disappointing others, etc. and she understood that. For my son, it's like speaking a foreign language. Your child's response could have been from my son. Hang in there - it's more about adapting your parenting style than anything being "wrong" with the kiddo. At least it's helped for me.
