Why my MacBook does not power up

Hello, I can not turn my MacBook on, I press the on button, but nothing happen, the only sounds are, a weird sound, which I think that is the Hard Drive, and a sound of the Fan, but the screen is black, then the computer get completely off and I can not turn it on, I took the MacBook to an Apple technician, but he said that the MacBook does not have problems, I don't know what to do, I'd like to know if it is a Logic board problem or what can I do, Please help me !