Hi my friend has a macbook. She was having a problem booting it up. the screen would just go black and nothing would happen when powered on. she took it to best buy to have it diagnosed. They told her it was her motherboard and that the laptop was basically useless now. they said it would be cheaper ot buy a new one rather than fix it. I find this hard to belive. Is it possible to fix it? and if so how hard of a task is it?