Gripeisme, any luck with your customers 540.
I encoutered the same problem tonight. Online with Dell, removed all expansion cards, memory and disconnected the hard drives. Still same problem. Power goes on, fans spin for a second and stop. I have in house service and they plan to replace power supply and motherboard.
Any resolution to this ( I know, Im a newb resurrecting this thread )
I noticed a loud fan noise in my Studio 540
I ran a vaccuum in it yesterday to clean out the dust bunnies,and we have had 5 or 6 power outages over the last week in this area, so figured something might have been damaged. ( I do have it running off a UPS )
Now I go go turn the box on today and the fan spin for 2-3 seconds, then stop, little green light on the back goes out - seems like same problem you are/were having.