Answer to: 27" iMac doesn't boot past white screen, not-responsiveOr you could just turn it over to apple and get its replaced for free :) https://support.apple.com/en-us/HT203787
Answer to: 27" iMac doesn't boot past white screen, not-responsiveThx for writing this article - had the same problems. And actually repaired earliere iMacs 27. So have a bit of insight in the tech. But was getting grey hairs over this one, and wen't through all possible scenarios (as you) then after two days found this o/ :) Thanks again, will contact Apple tomorrow.