Tell the kids parents, he punched your laptop and broke it. Long and short. He is at fault, and he should (his parents) should pay for a replacement.
Laptops have many components under the keyboard, everything basically. He could have damaged the motherboard, cpu, cooling system, ram, anything. Leave it up to his parents to fix what the kid damaged. If you really want to go deep, contact a service representative for your laptop, and have them bill the parents for what the kid damaged.
This is the right thing to do. No kid should have the right to go about punching peoples laptops and get away with it. Its no worse than him taking a cell phone out of your hand, and throwing it to the curb and stomping on it.