I updated my late-2013 MacBook Pro from macOS Sierra to macOS High Sierra this morning. The update ran fine and I got back into my system everything looking ok.
Then I shut the MacBook down to go to work. When I tried to boot it up again I end up with a black screen and nothing to happen further. (In detail: The screen turns on (apple on back is bright). I hear the boot up sound. Then nothing happens. The screen stays turned on even if I remove power and close the lid. Only pressing power button for a view seconds turns the MacBook completely off. Another interesting thing: when I let the MacBook stay in this black screen state for a while I start hearing the cooling ventilator running at low power which suggests that the MacBook is making use of its computational power but does not display anything)
Any ideas what to do now? (of course I have a Time Machine backup on an external drive but I don't have an idea how to make use of it at this point)
The macOS partition was encrypted with FileVault and a modification: only he root user can decrypt it
Also there was a Boot Camp partition with Windows 10
It seems like pressing Option key works and booting the Windows partition works!
When I press the Option key I can select between Windows and Macintosh HD. Menu works fine. The second I press Enter on the Macintosh HD it seems to freeze. So maybe it's related to the encryption?
I managed to boot into my time machine backup using the boot menu with connected backup drive. Using the Disk Utility I found a crazy fact: It seems like the macOS partition is gone. Not sure if this is normal (could be because Disk Utility can't read the encrypted partition?)