My iMac screen won't turn on?

so basically my iMac informed me I had updates to be installed so i installed them. Then I had to restart so I did. When I did the mac shut off... so I attempted to turn it back on... it wasn't off so I pressed the on again and then I heard the chime but the screen didnt and still wont turn on!!!! I can't do anything about it and I really need someones help... the iMac is new... got it in May