The first thing you need to do is to find out why there is no display.
Two main causes are;
1. the computer has hibernated or gone to sleep, if it has you need someone to explain what the difference is and how to wake the computer. this is controlled under Power Options in the control Panel.
2. it's Broke, as it is under warranty DO NOT MESS WITH IT it will void your warranty, I know it will be a pain but you should return it for repairs or replacement