"Differently" is an adverb, so in this case it modifies the verb "say." Thus he must mean that he meant to say something in a different way. By "something" I don't think he meant the word "something" so there is some unstated message that he wanted to give in a way that differed from . . . what? Did he mean that he had already been expressing this unmentioned thought, and now he chose the banner as a different way of expressing it?
Perhaps he meant "something" in the sense of "I don't really care which thing." Perhaps he felt that he had been in a rut, using a fixed means of expression for all his utterances, and he wanted to say something -- anything -- differently to break the monotony.
We get a hint from the fact that he added that it had a different effect. Different from what? He didn't say, but he added that it gave the wrong message.
I suppose he's just trying to say, "I made a mistake, but there was an innocent reason for it." So far, he hasn't articulated the innocent reason in a way that I can understand.
