Either you don't have the memory seated properly(easy to do), have the wrong type of memory, unplugged a fan or jumper(again easy to do) or you damaged the internal components (ie motherboard, processor fan. Tear it apart and give it a good look over.
As advertised. A++ tutorial. It is worth noting I do have a mechanical background. Looking it over though unless you used a magnet, got the components wet, or static shocked something, you should have no problems.