I corrupted my brothers laptop
Why did you corrupt his laptop?
I had no reason, I just wanted to see if I could do it.
There's never a good time to use your siblings personal things as a test for something that causes damage. Your brother is going to find out it was you and never speak with you again, so you need to come clean and apologize because what you did was very wrong and most likely hurts him a lot.
WOW, I didn't even plan this, it's not my problem, who cares.
I think he cares if you did ruin his laptop. I just think you should say sorry because I'm sure that laptop was expensive.