POWER won't come on...

Everything is as it was... no changes. But the computer will not boot up. Pushing the button on the tower: the light will stay on only as long as I hold it down, but will not kick start the computer. It's as if it's getting no power. HELP. Not panicking but concerned about all my data on the drives. Is it just an internal power supply that's dead (tell me the drives are okay!)?

Rick:
It's really easy to reset the PMU, though I agree that the instructions at the Apple link are both intimidating and could have been written better. The only tool you need is your index finger, and you'll be able to do this in less time than it will take to put your Mac in the car to take it in.
You've already added RAM and a hard drive, which makes you eminently qualified as a tech guy!
Here's what you do:
Shut down the Mac.
Disconnect everything on the outside of the Mac except the power cord.
Touch a metal slot cover on the back of the Mac in case your body might be carrying a static charge. This would discharge it through the chassis and the grounded power cord instead of perhaps some component on the logic board...
Now disconnect the power cord and open the side door.
On the logic board, look for the battery. It's 1/2 "AA" size (a "shorty" AA battery). The battery will most likely be either purple & green or yellow, which sticks out like a sore thumb.
Once you've located the battery, look in the immediate vicinity of the battery for a tiny round button (it's a microswitch) on a small square base. This button will most likely be either black or blue and is 1/8" in diameter.
Press down fully on the button and hold it fully depressed for a five-count. Then let go and don't press it again until after you attempt a startup.
You have just reset the PMU.
If you have a voltmeter, now would be a good time to test the battery. You can test it in place and don't have to remove it. Just remember that it's sending a small charge so keep the metal probes from touching other logic board components and possibly shorting something out. If you don't have a voltmeter handy, skip it for now and come back to it later on.
Close up the side door, hook up the power cable, keyboard, mouse, and monitor and attempt a normal startup.
If for some reason the Mac still fails to boot, please post back.
Gary
1GHz DP G4 Quicksilver 2002, 400MHz B&W rev.2 G3, Mac SE30   Mac OS X (10.4.5)   5G iPod, Epson 2200 & R300 & LW Select 360 Printers, Epson 3200 Scanner

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