If you are neutral in situations of injustice, you have chosen the side of the oppressor. If an elephant has its foot on the tail of a mouse and you say that you are neutral, the mouse will not appreciate your neutrality. Bishop Desmond Tutu
With no front LED, no gong and no video out, your G5 is not powering up. Make sure your connections are good and tight. Might be Electro-Static Discharge (ESD) damage if you didn't take precautions. I've had the small front circuit board go bad on mine before and saw the same symptoms.
PowerMac G5 dual 2.3GHz (PCIe), OS X 10.5.8, LaCie 2port eSATA, FW800 boot.
iPod Touch 1G.
Whoa...before jumping to conclusions you need to determine whether this G5 has actually leaked. Sometimes the leaks aren't easily visible - they weren't in my G5. It's a known issue, though not one Apple has gone out of their way to publicize.
Apple is repairing these machines for FREE - even if they're long out of warranty as mine was. Or, if you're very lucky, as I was, they'll give you a new Mac Pro.
In my case, my G5 powered up (no bong though, if I recall) and then gradually the fans would rev up and up until they were running full blast. It sounded like there was a bit of drive activity early on, but nothing happened - no video signal etc.
I took my G5 down to Carbon Computing - who at the time (Nov. 2008) weren't aware of the leak issue and Apple's response, but should be now. They'll charge $65 or so for the diagnostic, which will be waved if it's an issue covered by Apple. Worth a try. And you will find out what is the matter regardless of the cause.
Do read the linked page below at xlr8yourmac.com - particularly the bit about what to stress when calling Apple, if Carbon do diagnose a coolant leak. It's a SAFETY issue. That, and the fact that the processors were out of stock at the time my G5 needed repair is the reason I was able to get a replacement rather than a repair. (Told them that I did 99% of my work on my G5 and several weeks waiting for a part on a machine that had a design defect was NOT acceptable. I was polite but firm - and am still surprised that Apple gave me a new Mac Pro!) You may need to advocate for yourself on this - Apple would have paid for the repair for me once Carbon talked to them, but the time was an issue, so I decided to call them myself.