Admin status lost after username change
I bought a second hand imac a week ago. It's an old 2011 imac, with High Sierra installed.
I tried to change the username of the user (which was "azerty"...) using the user and profile tools, but when I restarted the mac as requested, I noticed that :
1) the username wasn't changed. 2) it's not admin user anymore !
It seems to be a know high sierra bug...
So I now have a mac with no admin account... I can't install software nor create folder/ copy/paste file in the backup disk....
I saw that there is some workaround using Single user mode, but now comes the tricky part... I then realized that the mac is EFI locked.
I contacted the seller, he said he got it couple of years ago from nearby company when they closed business.
What can I do, is there any way I can get an admin account back on this computer?
can you help me ?
Thanks a lot
Ist dies eine gute Frage?