Ok so, this is a fairly long one, any help would be appreciated. Last week I decided to update my Apple MacBook Pro Retina Early 2015 to High Sierra. At the time I was working via an external display, a 6 month old Samsung 27" C27F591. After updating to High Sierra I found the external display didn't work. Pretty confusing. I tried my TV, other HDMI leads, nothing. So decided it was the OS. Rolled back to the factory OS Yosemite 10.10. Still nothing. Tried 5 different HDMI leads, 5 different monitors - still absolutely nothing. Reset SMC, Reset NVRAM, tried the Safe Mode trick, Hardware Diagnostics returned nothing. Now this is where it gets weird: I take it to Apple's Genius bar to diagnose this because I'm tearing my hair out. The guy carts this monitor out the back (fairly old tesco brand LCD monitor, nothing fancy, modern enough to have HDMI mind)... I think you can see where I'm going with this. It works with no dramas! "Embarrassing." says the genius. Tail between legs I bring it home, thinking I must have dislodged some muck from the HDMI port and everything must be gravy again. It doesn't work. Nothing works. Different leads, different monitors - still absolutely nothing. At this point I'm considering bidding for the crap old monitor from the Apple shop!! Any help would be greatly appreciated, three magic beans to the guy or gal that solves this one for me :)
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