I would like to describe the funded project of someone incompetent who has failed to properly complete it mainly due to his incompetence but who has managed to present it in its failed state as a success even though it is essentially useless and bears little resemblance to the pre-agreed specifications of the project.
While it's most commonly used in a political context, I think spin control can be used to describe your situation
The shrewd management of the way in which a piece of news or information is presented or interpreted so that it best serves one's own interests.
You could say
The project was a useless failure, but the spin control made it appear as if the project was actually successful.
From Wikipedia, the phrase smoke and mirrors describes "any proposal that, when examined closely, proves to be an illusion." It comes from a common technique used in magic shows to make objects appear to float in the air.
In your specific case, you could say something like,
He put on a great show for senior management, but in the end it was nothing but smoke and mirrors.