on 8 October 2016 I purchased a new 27” iMac. 4 months after purchase it wouldn’t boot. Took it into Apple store and they said the logic board was bad and replaced it. That was March 2017. Just recently I tried upgrading to high sierra from el cap. It fails 10+ times. I finally took it in on Monday 2 days ago with clear description of the issue. They called yesterday and said it was ready for pickup. I asked what the issue was and was told that it was a software issue and needed to be wiped and reinstalled. I said ok and picked it up. Upon startup I found all of my data on the machine. I looked and found they had not updated the system as I was told. In fact they did nothing. I called the store was told that the tech started it up and it booted so assumed it was fine. Did not even touch it. He then suggested I wipe it and if it didn’t work to bring it back last night. I wiped it and after restart it now was stuck on constant restart load 90% then restart. I took it back to Apple last night and was told they would again wipe it and do a clean install. I told the tech that I researched the restart issue and it came back as logic board. I asked if it could be logic and he said no. Said I could pick up this morning first thing. Fast forward to today. No call so I called them. Was told that they were now seeing the same issues I described but were still in testing. At the end of the day I got a call back saying that they aren’t sure of the problem but acknowledge it exists and would do me the favor of replacing the logic board AGAIN for $550 my cost. I’m blown away this is apparently the new Apple. Has anybody experienced this? If so what was your solution?