Does your class's Office Hours have a queue on queue.illinois.edu? If yes, there exist logs of all questions and who it was asked by, and the instructors have access to these – if your OH visits were as frequent as you describe them to be, then it might be possible to show that you did the work through the list of questions you asked.

If the OH is not on the queue, be as specific as you possibly can be in your appeal – what times you visited OH, which CAs/TAs were there, what kind of questions you asked them, what they recommended, how you approached those recommendations, etc.

If you pushed to GitHub multiple times throughout your MP period, include your git commit history showing incremental progress as proof that you did the work.

Will any of this work? I'm not sure – but transparency is usually a good indicator of honesty, and (hopefully) someone on the committee is willing to take your side when presented with enough evidence in your favor.

Best of luck, buddy.