I recently acquired a B&W G3, looks stock from what I can tell. At power-up, it chimes but does not get farther than that. USB ports not sending power. It recognizes reboot command from ADB keyboard. I tried booting without video and only one stick of RAM, still refuses to boot from CD or HD. What might be the problem? Is it possible it's the PRAM battery? Tried resetting PMU, but I can't zap PRAM because I'm not getting the second chime.