Mac Crashed during High Sierra Update - Won't reboot My mac was turned off during the High Sierra update and now just gives me the flashing question mark when I turn it on.

If I boot into recovery I can't select my startup disk because the OSX Base System disk image is 'booted'. It won't let me unmount it either.

I can see my start up disk but I can't boot into it.

Can anyone help with this?
FTW if anyone is experiencing this I solved it by running the “faulty” computer on target mode and using its disk a boot disk on another MBP did all the update process with no problem at all. Then restarted and it came back to life.