Hello,

So , the special round is not conducted by JoSAA rather it is conducted by CSAB .

Now for your question the answer is no. You cannot change your category  in any round as you have already completed all procedure with open category. Most importantly any category like SC/ST/OBC can be changed to open but the vice versa is not possible. As it happened in your case because you could not upload you category changed to OPEN .

Hope you got your answer.

Good luck.