MacBook 2015, system password problem
My wife’s MacBook does not allow system preferences to respond to the computer username and password following her work admin trying to update her os yesterday. Apparently he tried to install Monterey, and the machine would not work at all. I re-installed Big Sur last night and the machine is now working but I cannot access system preferences at all. lots of trouble shooting, have reset passwords successfully but still same problem. Have tried terminal in Recovery mode and tried to enter rm “/Volumes/Macintosh HD/var/db/.applesetupdone.” That results in No such file or directory. Also tried that with AppleSetUpDone, with the same result. Have spent some time with Apple Support but our poor mobile reception ended the call before any resolution. Does anyone have any ideas?
MacBook