First, this should be posted in the Free Clinic
, not Help me Buy/Build.
Second, I can't believe being nice to it didn't work - that's usually the magic elixir!
Still, there are many components that could be wrong:
*Power could be one problem. Be sure you have it plugged in and not just on battery power.
*Is there a way you can hook up an external monitor to your build, instead of the laptop monitor? The laptop monitor (or the cable to the monitor) would be my next suspect.
BTW, using the known good RAM was a very good idea.
As a last resort, you could drop off at a local computer repair shop. One near me only charges $35 to diagnose - yours might have a similar price. I recommend doing this before you start shipping components back one at a time until you find the bad one.
Hope this helps.