I've got a PowerMac G5 DP 2.0ghz (June 2004) that is completely dead. When I connect the power cable the power supply click-clicks, but that's it. At first the power light would briefly light up, but it has stopped doing so. There are no diagnostic lights either. I verified that I'm getting +5vdc across pins 1 and 23 on the power supply and I've replaced the PRAM battery (which was missing). I'm not sure what else to check, could this be a bad power supply, logic board or something else? Thanks!