When students takes the test yet does not submit any written material the system automatically grades 0/40. can this be reversed? Can the student take an another exam for they had problems with their internet? Is this a thing to change the grade ?
Yes, just add a "user override" and the student can retake a quiz. You might need to also change the settings of the quiz to allow multiple attempts and set it up to only count the grade of the last attempt. I also like to check on the box under question behavior so that "Each attempt builds on the last" which will copy whatever answers the student had started into every new attempt.