Hi Eric, presumptions are dramatic, but not always helpful. Try starting your G5 with Apple's Hardware Test:
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Using Apple Hardware Test
You can use Apple Hardware Test to help determine if there is a problem with your computer’s hardware.
To use Apple Hardware Test:
Disconnect all external devices from your computer except the keyboard and mouse. If you have an Ethernet cable connected, disconnect it.
Insert the Mac OS X Install Disc 1 that came with your computer.
Restart your computer and hold down the Option key as it starts up.
Click Apple Hardware Test when the list of available startup volumes appears.
Click the right arrow.
When the Apple Hardware Test main screen appears (after about 45 seconds), follow the onscreen instructions.
If Apple Hardware Test detects a problem, it displays an error code. Make a note of the error code before pursuing support options. If Apple Hardware Test does not detect a hardware failure, the problem may be software-related.
For more information about Apple Hardware Test, see the Apple Hardware Test Read Me file on the Mac OS X Install Disc 1.
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Hi Euan, you were probably think of an earlier version of OSX; I have only the one Install disc (Leopard) & the hardware test is not one of my options. I did take the opportunity of repairing all the disks, and I did try plugging the camcorder into a Firewire port and switching it on, but with the same result.
There are various ways Apple has made the Hardware Test available
(see: kb/HT1509)
It seems that as you are missing the grey installer discs that came with your G5 - you need Disc 1 - you are out in the cold as it were, unless you can borrow the disc. The Knowledgebase article has a review of the different access methods, but the Leopard Retail Install disc doesn't appear to have the test software available on it, at least for G5 PPC models.
From what you say your Firewire does seem to have failed, so it's probably not worth pursuing the Hardware Test.
Eric Jervis 