HP/Compaq Presario won't power on

I have a Compaq Presario SR1010Z that I powered down, moved 10 feet to a different table, and then tried to power it back on and it won't power on.  No hard drives spin up, and the motherboard never gets power.  The power supply fan never turns on, so when the power button is pressed, nothing happens.

This computer has a Bestec ATX-300-12Z power supply, and an Asus K8S-LA (Salmon) motherboard.

1) I have disconnected all connectors except for the motherboard, and it still does not power up.  Thus, the power supply is not overloaded.
2) The back of the power supply has a green LED light.  It flashes very quickly when the motherboard is connected.  When the motherboard is disconnected, it stays lit (does not flash).
3) I recall having this problem happen with this computer 4 years ago, and I cannot recall what I did to fix the problem, but I was able to get it running again without changing any hardware at all.
4) I have searched online boards and HP's website for hours and have only found the rudimentary "gee, replace your power supply" comments.  I have seen a percentage of people who HAVE replaced their power supplies only to have the computer exhibit the exact same problem which leads me to believe that there may be a power problem related to the Asus motherboard.
5) A call to HP support did not produce any results (the machine is way out of warranty, and I was happy that they tried to solve the problem without charging me though!)
6) I have removed memory from the motherboard to see if it made a difference.  It did not.
7) I removed expansion cards to see if it made a difference.  It did not.
8) I followed HP's advice on their website relating to unplugging and holding the power button down for 10 seconds and then attempt to turn on.  It did not work.
9) I have set the jumper and then un-set the jumper to clear the CMOS settings on the motherboard to attempt to get it to boot.  It did not fix the problem.
10) I have bypassed the power button by using a screwdriver to short the power jumpers on the motherboard to see if I could get it to power up.  This did not fix the problem, so I believe the switch is functional.

I am suspecting that the problem is somewhere in the motherboard, but I don't know which way to go from here.

I also have a suspicion that the problem may go away after 24hrs of power being unplugged (perhaps a capacitor or something needs to be fully drained, or a over-voltage clamp needs to reset).

Does anyone have any other ideas?
Tim TitusCTOAsked:
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RartemassLife CoachCommented:
Check if your capacitors on the motherboard are OK. A bad capacitor will generally either have bulge on the top, or a ooze gunk at the base.
This site can help identify bad caps:

If they are OK, try the power supply with a different motherboard (if you have a spare one, or a friend that doesn't mind using their system).

If you know how to use a multimeter you can check if the PSU is providing the correct output.

Try a different power socket in another room.
note that bad capacitors are common in the power supply too.
i suggest to swap the PS first to test - you can use any old ps of 300 W or more..

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Imran SaeedIT Technical DirectorCommented:
If it flashes quickly when you plug in to the motherboard it indicates short on any of the power line so most likely the motherboard is gone.

you can get another motherboard and test the processor and ram to confirm this.
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Tim TitusCTOAuthor Commented:
The motheroard & power supply could not have gone bad between powering down the system and moving it 10 feet to another table.  This "problem" happened to me ~4 years ago, and I didn't need to buy a new power supply or motherboard.
I smelled both the motherboard and power supply immediately after trying to power up, and there was no "burned capacitor" smell (I'm quite familiar with this smell, as I've had blown power supplies over the years!).
I also tried three different outlets, and verified that the outlets had proper grounding.

Additional information:
The computer used to be plugged in to a UPS (APC BACK-UPS RS 1300VA LCD 120V).  I can move the UPS to the new desk and try, but I don't have a lot of faith that that will make much of a difference since this model of UPS is passive until power is lost (does not do line conditioning or anything until it detects low voltage).  Fee free to add your thoughts regarding this fact.

Additional suspicion:
We only powered down this computer when we went on vacation.  I'm leaning towards leaving the computer turned off for 24hrs and then trying to turn it on again.  The only time I recall having problems with turning this computer on was when I turned it off, took it outside, blew out the dust, and then attempted to power it back on (all within 1 hour).
i never said the power was bad - i only suggest to swap^it to test
>>  I smelled both the motherboard and power supply immediately after trying to power up, and there was no "burned capacitor" smell (I'm quite familiar with this smell, as I've had blown power supplies over the years!).
    <<  that is not conclusive...

>>  We only powered down this computer when we went on vacation  <<   very bad habit imo - if the power gets bad, you'll see it if you power on regularly (also VERY bad for environment)
RartemassLife CoachCommented:
Have you added any hardware to the PC from the standard components when you bought it?
A 300W PSU may struggle if you add in too many cards and drives.
Considering you always leave it on, if the PSU was running at high capacity the entire time, it may have burnt something out.

PSUs have a Mean Time Between Failures of somewhere between 50,000 and  100,000 hours at normal operation. This drops when at peak load for  extended periods.

Even though it happened 4 years ago, it may have been for a completely different reason (loose cable?).

You don't have to purchase a new PSU to test the old one. Simply borrow a PSU from a friend and try that in your system. If you can't do that, you can check voltage etc with a multimeter. If you don't have one (or the knowledge to use one) then you can take the PSU to a computer or electronic store and ask them to test it for you. Most will do it free on the spot as it only takes a minute.
This will rule out the PSU issues, so then you can move onto checking the motherboard.

RartemassLife CoachCommented:
The below link has several flowcharts that give a fair indication of where the issue may be.
Go through them and see what response it comes up with. It may point you in the right direction.

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