We all have to wait. It is usually the longest wait in the late evening when students are logging on and entering their answers for assignments. This is system wide and not just your students.
You can vary the amount of points for the right answer, but you cannot grant any points for any of the wrong answers. You can WITHDRAW a question and grant credit to all students.
The question will have to be re-edited and saved with the correction. Unfortunately, for you and your "bad" version of the question, it will not ever be fixed on that assignment. Get the problem fixed and it will be ready to use NEXT time.
So 65% of your class missed question about free energy on the exam? You have no way of knowing WHICH of the wrong answers they picked. You DO know that 35% of your class got the question right though.