Hi guys, I bought a brand new rMBP 15" from the Apple Store Regent Street, London on Saturday (1st November). I turned it on this evening and I simply got a black screen on bootup. Understandably I'm very worried; is there an easy fix or does it require a replacement? It's barely 5 days old! The starter bong sounds but then there's nothing after that. I've rebooted three times but still nothing. I hope someone can help! Thanks in advance.