Have you considered using incentive rather than negative reinforcement or punishment? Perhaps he doesn't respond with desired behavior in response to threatening his grade because he nor his parents care about his grade. Maybe introduce something that he does like or care about, to encourage the proper behavior. This is something I tested in an ABA case study.

Ensuring to abide by the classroom rules and consequences that were determined on the first day of school is essential in this particular situation. It is important that if a student, especially this one, breaks one of the classroom rules, they receive the appropriate consequence that is attached to this rule. If this still does not seem to work, you could always put this particular student on their individual behavior management plan. If this student gets so many check marks during the day and/or week, they could be given some type of reward, that is discussed with the student and something that truly interests this student, at the end of the week. If this still does not work, you could then have a meeting with administration and ask them to sit in with you while you conduct a parent-teacher conference with the student's parent to discuss their child's behavior.

I would suggest to observe the students favorite things to do or favorite sports. If you found out what it is, you can have a friendly competition that is related with the lesson. Maybe this time he will be challenge and will pay more attention and show some care in your class.

I would try to focus on positive classroom behavior. I would give the whole class an opportunity to earn a sticker, owl, marble, or something for positive behavior. At the end of the day put their reward in a bucket, or pocket that is labeled with their names on the. Then on Friday those students who have a total of four to five rewards in their buckets or pockets can earn treasure box or whatever incentive. Praise the positive behavior, and keep encouraging the class as a whole.

Try using positive reinforcement. My students are very food motivated so if I offer snacks, they participate.

Always turn a negative into a positive with students who do that!

Positive reinforcement would a great way to motivate this student, as stated in another post, if the parents don't seem to care then the student may not receive any positive feedback or any attention at home. If this is the case, then the student will accept any attention given and if you can positive attention would build a trusting relationship with him and intrinsically motivate him to want to better in the classroom. You may be the only one who gives them positive attention which would go a long way in the classroom.

I would create a plan in my own classroom where he will receive some sort of punishment example, 5 mins. out at recess, no free time, new assigned seat, etc.