The other day I accidentally messed up updating my iMac from 2010 and have seemed to uninstall macOS.
I have successfully made a usb boot drive for Sierra (the os it was on prior to this problem), but when I open Utilities in recovery mode and click install macOS, I get a “The operation couldn’t be completed. Permission denied” error.
I would try and go into internet recovery mode but unfortunately that feature doesn’t work on Macs this old. I would also try to just reformat my hard drive but I need all the data on it. What can I do?