Sounds like repair may not be your forte.
Well I've only been repairing them since 1979. Yours may not have been made by the devil but it sounds like it certainly been worked on by something akin to one. As a pastor as well as a Mac repairman I can perform an exorcism on it, attempt to purge it from the curses that almost certainly have been heaped upon it. For those services, I do not charge. But for replacing the logic board, I do charge, Apple most likely will not touch it except for a price close to the cost of the whole thing. I usually do not solicit business on this site and this is really not a solicitation but an offer for a solution. Click on my icon and email me. Tell me the truth about why you were even in it in the first place and what else was damaged. I'm 97% sure I can get it working for you at a price better than you will find elsewhere. It sounds like you will need a real expert to resurrect it.