It could be misconfigured ram, CPU not seated properly or bent pins, the PSU isn't powerful enough to power your system. You need to see if you can get your board to boot with just the CPU, ram, & GPU and go from there.
Removed the battery and reinserted. Nothing. I don't know why, but I removed the power connectors to that said EATX 12v. When I did that, the system powered up, but nothing happened as far as boot sequence. What does this mean?
Check the CPU Power Connector(8/4 Pins power)... Also, Pull those power connector and push back in until you hear a click... Also, check and see if your Power Button doesn't have anything inside of it my taking the front of the case off...
If you can get your hands on another PSU, you should throw that it and see if it still occurs. I fixed many computers with this issue and 90% of the time it was the PSU. Other times it was mis-seated ram, case leads messed up, or a bad CPU fan.