£2000 laptop that's served me well for 18 months has suddenly stopped working. Never had any issues prior to this and was working fine last night before I went to bed.

If I turn the laptop on, the power light comes on, stays on for 2-3 secs and then goes off. CPU fans don't spin up. HDDs don't whirr. Blank unpowered screen.

Tried using one stick of RAM at a time with no change.

Ideas?

I'm assuming it's not overheating as I don't think it's possible to do that in such a short space fo time. Plus the other symptoms point elsewhere.
It could be the PSU brick. A lack of power could mean there isn't enough for the fans or hard drive. I don't suppose you have access to another one with the same spec to test the laptop with do you?

You could always send it back to the manufacturer for repairs. I sent mine back to Sony to be repaired after the power button was broken after a flight to/from work. It cost £150 ish to repair, but it was only six months old at the time so it was worth it.
If it's under warrenty and the problem wasn't casued by you damaging it, it should be free.

It still happens if I try to boot off the battery. Have currently requested an RMA. Paid for three years' warranty.

In that case, don't start taking screws out

Seems to be fine now.

Just to update:

It stopped working on two more occasions (each for a couple of days) so I decided to RMA it. The company said the battery was flat, charged it and it seemed fine. They could only replicate the fault if the battery was near-depleted but it held its charge fine overnight.

Seems odd.

Got it back anyways and it's just a massive improvement going from my NC10 to this big beast.

Would it work if you take the battery out and power it up with the mains cable plugged in? (yes you can do that with laptops, some people don't realise)

Not with a lot of Apple ones you can't .

Don't think i've tried it on this laptop though have done on the old one. One of my mates used to run his laptop solely off the ac and the battery was kept for travel - meant it lasted a few years without depleting

It's certainly not all leptons that will run from AC alone - I've got a couple of old ones in the cupboard that need the battery to give them a boost to get started. It's probably more common on newer models now that AC adapters are so much more efficient than they used to be.