Why is my 2,5 year old baby brother having rage attacks?

First of all check and double check the childcare you are using. Temper tantrums are not unusual in a 2 year old and I certainly don't recommend putting him in his room to calm down, sleep is supposed to be relaxing, you have made his room a place of punishment. Get him checked out by a doctor that something isn't wrong physically. Also, is he getting enough rest? Little children are like puppies, they will run for so long and then crash and sleep - if he isn't allowed to do this he is quite possibly overtired and unable to control himself. See what the doctor or health visitor says