Re:corrupt PMU? (Score 2, Informative)

On the newer Macintosh computers (Blue G3 and above) you must be sure and press the button only once and for less than a second; if you press it more than that it will crash the PMU and the battery will die within a day or two rather than several years. The machine will still power on just fine, and you won't know anything bad happened, but the battery will be toast. Also, after you press it you only need to wait about 15 seconds. This info is straight from the Apple service manuals for those computers. Hope that helps!