Update:
I did all the above and it breathed life back into this imac! I was able to successfully flash the Nvidia 860M 4gb to work and it worked well but unfortunately it only lasted 1.5 years until the gpu failed again. This couldve been avoided by sanding/working down part of the heat sink since it didn’t match perfectly with the 860M. I already tried baking this one but no go unfortunately. @virv , I would go ahead and do it, mine was irrecoverable but I think its b/c of the poor match I had before that really messed it up. I had obtained the 860M for about $50 back in 2020 but prices are a bit crazy nowadays (its going for almost $180-200 used!) so I’ll just be getting a new mac with an M1 core. Good luck for anyone who comes across this later!