You have a bit of a chicken and egg problem here ;-}
You need a clean good copy of the systems firmware to make a copy of it to a new chip. As the firmware in your system is bad you can't make a copy. And, yes each systems EEROM is different! So you can't take someone else's EEROM to copy from and besides you'll need to desolder it from the logic board to put into a EEROM burner to copy it. Just the gear alone is a few thousand dollars plus the software.
Bottom line here: its just not economical to even go down this path. I would recommend you carefully put your system back together and bring the system into an Apple Store and see what they can do for you.
I should also point out the newer systems use a different chip which is much harder to burn. Apple and others have done this to help stop theft of systems just like they have done with the iOS systems one can now brick ones laptop & desktop if stolen.