Macbook Pro Everlasting Gray Screen At Boot

Hey guys, i'm not sure if this is the right section, but please help if possible.

Specs:

Model: MacBook Pro 7,1

Ram: 4GB, good condition (Well at least it recognizes when theres no RAM installed)

Has optical Drive

previously had OS X 10.6.8 installed + Boot camp

So basically... i was using this mac as a router since i got a newer one, but last time i reinstalled, i cleared the drive because of permission issues that were bugging me. Using a partition tool, i tried expanding the windows partition, but then the whole thing went haywire, by that, i mean it broke. now all i get on startup is a everlasting grayscreen, no chime, no apple logo, no spinning wheel.

Methods tried:

- Resetting PRAM/NVRAM/SCM

- C at startup with os x install dvd

- custom boot drive

- good'ol fashioned piece by piece reassembly (Including reslotting/replugging everything i can think of)

I've seen one similar case on the forums, however that was a RAM issue iirc. My mac recognizes RAM fine and does not even give a gray screen without it. I think it should be firmware corruption because it doesn't recognize devices/hardware and doesn't show a logo. However, the thing is i can't find a firmware restoration file for this model of mac. I'm clueless regarding what to do now, and if it involves new hardware/logic board and stuff... I don't know if it's even worth it.

Note: there are beeps when no RAM is installed, and the screen stays black in that situation.

Note: it is currently an Empty HD, nothing installed due to me wiping it before the incident

Thanks for reading to the bottom