Sounds like it's failing to POST. Does it have diagnostic lights, or giving you beep codes? Right off the bat I would ensure the RAM is installed in the proper slots as per the manual. Also make sure the 8 pin CPU power is plugged in & fully locked in.
If everything is on the up & up so far, I'd reseat the RAM. Perhaps try with 1 stick of RAM in the primary slot to test. If nothing, reseat the CPU. Ensure it's oriented properly. Don't bother with thermal paste until you get life out of it.