My PS3 won't start/boot up

I woke up yesterday and went to turn my PS3 on. It beeps for the power on but doesn't boot up and turns off straight away. I have tried holding power button in to do setting reset but it doesn't work, the lights flash from blue and green straight back to the red stand by light and nothing else happens. I bought it second hand 3 weeks ago and it has worked fine up until this. Please help as my partner skill kill me for wasting money on a faulty machine!!!!