PowerMac G4 MDD power button flashes but doesn't boot

My PowerMac G4 MDD will not boot when the power button is pressed. The power button lights up for about 1/2 second and then goes out. There are no noises at all. No hard drive spin-up, and no fan.
For the past few years, in order to get the machine to boot up, it has been necessary to unplug it from the power source and plug it in again. I have read about other people having this same exact problem and remedy. Now, however, doing the unplug/replug thing no longer gets the machine to boot. The power button will light up briefly only after an unplug/replug. Subsequent pushes will not cause it to light up until another unplug/replug is done.
I have removed all peripherals, including the video card (only card that was in the machine), 3 of the 4 RAM modules, disconnected the hard drive and DVD drive power cables, and disconnected the fan, and removed the PRAM battery (which I know is probably dead), and this makes no difference in the behavior: The power button lights up for about 1/2 second and nothing more. I also disconnected and reconnected the power supply cable to the motherboard. No difference.
There seem to be 2 possibilities: I need to get a new PRAM battery and press the PMU reset button, or my power supply has gone bad.
Before I buy a PRAM battery, I am investigating the power supply to see if I can tell whether it is good or not. Some people with similar problems have discovered blown fuses in their power supplies. Before I open up my power supply and look for that fuse, I have a question for anyone who had that fuse problem: Did your power button still light up, even briefly, when your power supply had the blown fuse?
Best regards,
Dave

Hi steff1920, and a warm welcome to the forums!
While you may get help or a solution here, It's quite acceptable to start a new topic of your own, certainly feel free to start a new topic to attract more helpers to your particular situation, here's a link if as is often the case, it's hard to find out where to do it...
http://discussions.apple.com/post!default.jspa?forumID=589
Hopefully we can get things explained.

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