Honestly, I think this convention was really just a "first, do no harm" exercise. It was never going to have any real pageantry or present a lasting image. Whole goal was for it to go off relatively smoothly and for Biden to give reassurance he's up to the task, which he did.
So I doubt it garnered him any additional votes. But it didn't cost him any, either. As he is ahead in the polls, that was pretty much the plan.