Is it my logic board, RAM, or hdd?

My mid 2009 white macbook wont display anything. i installed a 750gb harddrive about a year ago, and replaced one of the 1gb sticks of ram with a 2gb stick about 2 months ago. every thing recognized and it was running very smoothly until last week when i went to do a routine restart. the computer just stuck on the desktop with the spinning disk in the middle for a couple minutes so i just powered it down manually.

NEXT STARTED THE TROUBLE! it wouldnt start up after that. I can hear the hdd spinning and the dvddrive starting up and the light turns on. but thats all i get.
i was convinced it was logic board so i went on ebay and bought a used 2008 black 2.4ghz macbook thinking i could just take the logic board out of that one and replace my 2.13 ghz board. the guy said it was working all it needed was RAM, a hdd and the L bracket to cover them. he has 100% feedback so i am trusting him that it works. but when i put my RAM and hdd and L bracket from my white mac into the 2008 black one i just got yesterday, IT IS DOING THE EXACT SAME THING AS MY WHITE ONE!
he said it was working so heres where im convinced that it could be a faulty hdd or RAM.
Ive also heard of battery connection issues.

has anyone had the same troubles or know what hardware issue it might be?(assuming that its harddware)

ive tried a lot of combinations. trouble is i dont have an extra hdd to try since i dont know what happened to the original.

The white one is a goner i think. it doesnt even respond to the power button anymore. but i might have not put it together right so ill take it apart and resemble it and see how that one goes.

but i just tried the black one without the ram and the hdd in it at all and i did get the BEEP BEEP BEEP. does that mean that the logic board might be still good??? i still didnt get anything on the screen. i have a startup disk and i and used cmd R but that didnt do anything (now its stuck in there)

my main goal is to get at least one working computer out of the two lol

so i guess my question is, is that beeping a good sign? i almost crapped my pants in excitement when i heard it

another question is, should I get something on the screen at all, even without the ram or hdd?
are there any commands that I can use that might help?

Thank you so much for the reply guys. im new to this forum but ive always used it to look up stuff for my mac

I read somewhere that someone had the same issue and fixed it by messing around with the battery connections so ill try that as well.

are there any recalls for either the a1181 2008 2.4ghz board or the a1181 2009 2.13ghz board?

i swapped hard drives with my twin brothers mac and it loaded up, and the ram also and they all worked. so im assuming the problem is the logic board for both computers. I did manage to successfully swap logic boards. put the 2.4 into white mac that had the 2.13. i couldnt detach the video cables off the board so i had to take apart the whole mac to get the cables running up the screen too. pain in the ass but i believe i made some progress.

I got a screen flicker when i hit the button now, and i never got one of those before with either machine. idk what it means but my quest to fix it shall continue.

if anyone has found a cure for maybe a bad video card or tried anything with the power connections and got it working, PLEASE LET ME KNOW! I even tried the freezer trick but got nothing.

UPDATE

ordered a working 2.4 a1181 logic board and installed it yesterday. it was doing the exact same thing as what my other 2.4ghz logic board is doing. This makes me believe that the problem isnt the logic board.
but heres my question.
could the firmware in the harddrive that i have that was installed on a 2.16ghz processor not work with the 2.4ghz processor?