In the last week I've been having a problem with my Vostro 410 mini tower.
When power is applied to the box the green LED at the rear of the PSU and the amber LED on the main board both light up as normal.
Pressing the power button sometimes starts the system as normal, with the button lighting up steady blue, but more often all that happens is the button flickers briefly amber and then nothing, except a slight noise as if a fan is about to start.
Removing the power and retrying sometimes works, as does leaving the box for a while after first applying power. The other thing that always works is sending a WakeOnLAN message from another device on my network; the PC starts and runs exactly as if the power button was working.
Once started the PC boots and runs perfectly as before.
I have tested the PSU voltages and they are all within a few % of their nominal values. Also, unplugging the 24-pin ATX connector and shorting the green wire to ground starts the PSU.
I tried changing the on-board battery but the problem is exactly the same with a new or partly discharged battery or with none at all.
Can anybody please suggest a cause and cure?
