Power outage mid system update

[Laurie McCall]

My iMac was mid way through installing the new Big Sur OS update and there was a power cut/outage across our whole town. Now when I turn the Mac on I see this screen (see image attached). What should I do now? Any help would be appreciated! Thanks

 

[wilberforce]

I would try to Restore MacOS by turning on the Mac while holding down Command+R.

But I suggest get some others on this forum (or Apple) to chime in, as I have not personally been faced with this problem, and would not want to give advice that just compounds the problem.

 

[Laurie McCall]

Thanks, that worked. Big Sur is now reinstalling.