I'm having the same issue and the dell tech support guy I spoke with was less than useless.
The laptop was bought in November last year and has worked fine up until this morning. It powers up no problem, the keyboard lights up an the fan starts as normal, I then get to the dell logo but then it goes blank (not black) the only thing that lights up is the f12 boot image but when I press f12 nothing happens.
The dell advisor I spoke to asked me all of 4 questions before concluding it was most likely a game I had installed 2 weeks ago on an external hard drive (since this was the last thing I'd downloaded...) the solution offered was to pay £130 to re-purchase windows 8, since I paid over a £1000 for the laptop less than 6 months ago and it is still very much under warranty I told him where to go.
Any advise on how best to proceed would be appreciated, I have an older laptop I can use to download updates etc onto a usb if that's the best option or even a number for a technical advisor whose dealt with this issue before hand would be appreciated.
Thanks