Computer Science is not about how to fix computers its a huge and diverse field.
For example CS students study how computers work at the fundamental operating system and circuitry level. They study algorithms and how to create and use them to solve problems such as: efficiently searching through data, creating 'intelligent' behaviour for games, computer graphics (algorithms not MS paint) and creation of software from problem analysis to development and testing.
I even used Darwins theory of evolution(AKA genetic algorithms) to solve Sudoku
So don't think badly of your friend because he doesnt know how to fix a computer you can learn to do that without a degree as theres not much to learn. Theres so much that can go wrong on the software side that I.T technicians generally use formatting and disk imaging to fix the issue without understanding the problem. Any enthusiast can learn to fix a computer
Sorry about the lecture a lot of people don't understand what CS is and I was feeling sorry for your friend :P