Help pc won't start

[ben12321]

Hi guys think I've done a stupid thing today I was abt to install win7 on my pc formated hdd and went to install but it would allow me then I remembered last time I did it I unplugged my second hdd anyway without thinking I opened case and pulled out the sata cable which in turn the comp died when I press the on button the green light on the button will blink as I push it and the CPU fan briefly spins for a nano second and that's it.
I have a pb pc which is 2.5 yrs old q6600 CPU 3gig mem do you think I have done the mobo or could it possibly be the power supply and help would be greatly appreciated

regards

 

[ben12321]

I'm sure nothingwent behind mobo and all cables where they should b gonna take psu to mates tom and connect it to his system and hopefully it won't work but knowing my luck I think I will b looking for a new compy tom afternoon