Just a few questions to help you out...
1) Was the unit running (on) before it went dead or were you trying to turn it on after you turned it off?
2) Was the unit moved and during the move it went dead? (Possible broken power connector on the box)
3) Do any of the lights, fan, anything happen when you press the power button?
4) Have you removed the drives and tried to power it on?
5) When/if you check the voltages out of the power supply, check for AC ripple as well and report those values. If you have a failed power supply replacing just that item may not correct your problem. The drive box could have caused the power supply failure.
My advice is to call D-Link and get a new unit. Pull your drives and do the RMA. If you have specific setup information that you recall, I'd recommend you write it down so when the next unit arrives you're able to get your NAS back online as soon as possible.
-Joe