New Build Start up Issues

Alright so this is my first build and something seems to have gone horribly wrong, well not horribly but not well. Anyways, I'm having a problem where when I turn on the computer all that happens is the fans twitch a bit and then nothin' the LEDs on the motherboard are also staying lit up, but that's it. I've read the trouble shooting forums on here already and nothings worked, actually been googling for a while now.

Here's the build:
Intel i5 2400 cpu
Asus P8Z68-V LE Motherboard
Nvidia GTX 560 gpu
Cool Master 750 Wat psu
8 gigs of Ram

It initially didn't work and then a friend of mine rearranged the little cables for the power switch and reset switch and then it was fine, but today I took off the heatsink to put on thermal paste (because I forgot, though I hadn't had the computer on for more than a few minutes previously). Found out it already had it on it, but I changed anyways because I had taken off the heatsink I figured it made sense to do. But now the same problems happening again, the Fans only twitch when I try starting it up. I've also tried restting CMOS though I'm not sure It really did much of anything for this problem. And I did double check the power switch and reset switch cables again.

Any help would be great! thanks.