talk minus action = zero

I have questions about computer hardware in relation to this post. I thought my house mate's power supply had died, so we ordered a new one. When I installed it last night, his computer still didn't turn on.
Here's what happens; when you push the power button the power light flashes on then immediately off. Obviously the computer doesn't power on... To get it to do anything else, you have to turn the PSU off, then back on; and then the computer still doesn't power on.

Trouble shooting we've done includes, swapping out power cable, plugging it into a different outlet, making sure all connectors inside were connected by disconnecting them and reconnecting them, and we blew a lot of dust out using canned air.
I also connected a different power supply, one without a 12V CPU connector and everything seemed to work except the CPU fan didn't come on and (I assume) the CPU never got power. This is what made me believe that it was bad power supply.

So my questions are;
1. What are the odds that a new power supply would come DOA?
2. Could it be something else that I'm missing? If so, what?

X-posted to: c0mp_g33ks, computertech, and paintitmatt

My housemate's power supply recently died. I wonder if anyone has a spare. His system board is a PC Chips M825 V7.1A (more info here) and the power supply is a Maxpower PX300w version 2.03.
I have a few power supplies stashed away, but none of them have the right connector. Aside from the normal 20 pin connector, the Maxpower has a 4 pin ATX 12V power supply connector (according to the specs on the website). The system board's manual lists it at a CPU Vcore power connector. Basically, it's 4 pins in a square pattern which you can see at the top of this picture.
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So I'm asking if anyone has a compatible power supply they'd be willing to part with. I have spare parts I could trade.