<< Solved >> Attempting System Restart ... Mach Reboot

[whitecold]

I somehow broke my setup after upgrading my system from Sierra to High Sierra.
The update itself worked fine, but during post installation trying to get my external HD recognized and to get audio to work, after installing the kexts for audio and running Multibeast for the USB ports, my system refuses to boot.

It hangs at
Attempting System Restart ... MACH Reboot

I am unsure how to extract any files from my EFI partition since I can't boot. Any help is appreciated.

 

[UtterDisbelief]

I somehow broke my setup after upgrading my system from Sierra to High Sierra.
The update itself worked fine, but during post installation trying to get my external HD recognized and to get audio to work, after installing the kexts for audio and running Multibeast for the USB ports, my system refuses to boot.

It hangs at
Attempting System Restart ... MACH Reboot

I am unsure how to extract any files from my EFI partition since I can't boot. Any help is appreciated.

Use your UniBeast USB drive to boot the system. Doesn't matter if it is Sierra.

Suggestions:

1) Use disk util on the UniBeast installer to check the main drive.

2) If you can boot using UniBeast, using Terminal you can copy the EFI folder from your USB drive to the main one to get your system up and running (backup the one already there by renaming etc).

3) If you can't boot with UniBeast you should still be able to access the EFI partition and folder on the main drive using Terminal again, although it is a bit arcane. You first have to mount the partition etc.

4) If you kept your High Sierra install as HFS+ format you could possibly access the errant drive using Windows or Linux and a file system access utility on another drive etc.

 

[whitecold]

Late update: My USB stick was somehow not properly recognized, newly formatting and setting it up as UniBeast Boot stick allowed me to boot the computer, and use clover to properly configure the EFI partition