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Does anyone know how to downgrade the firmware of my Macbook Pro 15" (2014)? I ran the Big Sur Beta 1 with it on an external SSD drive. Since then, the standby
by xenonite 6y ago
Does anyone know how to downgrade the firmware of my Macbook Pro 15" (2014)?
I ran the Big Sur Beta 1 with it on an external SSD drive. Since then, the standby mode on the internally installed macOS 10.11 does not work anymore. At some point, the system freezes while the fans spin on full speed, indefinitely until powering down with a long-press of the eject key.
- peterburkimsher 6y agoThank you so much for warning me: I have the same model (2014 MBP 15"), and would very likely have tested booting an external drive with another OS, not expecting it to cause harm to my hardware. Maybe this will help; the instructions are for Yosemite though. https://forums.macrumors.com/threads/guide-how-to-get-back-old-efi-after-downgrade-from-yosemite.1803934/ https://forums.macrumors.com/threads/guide-how-to-get-back-o...
- xenonite 6y agoThank you very much for your hint. So far, it seems that the downgrade did not succeed. The boot ROM number is still the same after the manual patch.