Good luck trying to get any help from Apple since it sounds like you have taken apart the computer already and you're out of warranty. In my case, my hard drive was running fine in another machine so I tried to torch the chip to reball it myself and that failed. I figured I didn't have anything to lose at that point. Since that didn't work I ended up sending the card with the bad GPU chip to Brickfence on Ebay and having the card replaced with a new chip. Brickfence told me both the chip and card were bad. I had them replace both items since you can not find new cards any longer. Their products came with a warranty and the service was great. I got a replacement card and chip for $349. Much less than replacing the machine.