i build my own computers but never put a laptop together i just assume its a little smaller of a build. i also dont go mac either, hate the **** out of it. its very rare laptops make it 5 years so it could actually be a number of things, but if it doesnt fire up at all i would first check your power supply, if that works then go to the mother board and check for breaks in the tiny electrical lines that run all over, or if anything became too hot and connections need to be re-soldered (if thats needed just get a new laptop) then from there you pretty much just have your ram and processor which it looks like you have knowledge of this stuff so i might not even be of much help but i hope its your ram issue, although any ram issue ive had my pc still fires up.
I guess i should maybe ask by "fires up" do you mean it wont turn on at all or does your computer come on but your operating system never loads?
and i supposed i should read more, missed your last post. looks like you've got it under control!