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Hello guys. It is problem from Catalina Update. Catalina damaged efi firmware on logic board. I have same problem in my Mac Pro 2013, when I update to Catalina I receive black screen. But we have 2 Mac Pro 2013 and we create dump firmware efi from logic board from working Mac Pro, after we flash firmware on damaged Mac Pro through special programmer which I buy on Ali express for 5$. and after this manipulation my Mac Pro alive. I hope this information helps you.
P.S. Before my manipulation I call in apple service and they say me that need replace logic board for 600$. And say that I myself to blame for this problem. But im say him that my Mac Pro will live before update to Catalina, but they didn't care.
Link on Programmer - https://ru.aliexpress.com/item/32725360255.html?spm=a2g0o.productlist.0.0.4e3627d4vfZjsf&algo_pvid=172870e4-70b0-43af-bd61-a47c604cfee3&algo_expid=172870e4-70b0-43af-bd61-a47c604cfee3-0&btsid=2a1c810a-56e0-4800-93fd-129b20831300&ws_ab_test=searchweb0_0,searchweb201602_4,searchweb201603_55
Soft for flash: flashrom
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Before manipulation please read documentation for this device. Because there have are many subtleties
WARNING! Need create dump from same logic board from same Mac, it is very important.
WARNING! And don't forgot that need change in efi dump serial number on you device. You can find this video on YouTube.