cp-xcvi wrote:
About the Internet Recovery Mode, I do that to reinstall Mac OS BUT I only get the option to install Mac OS Big Sur BETA...
Even if you use Command + Option + Shift + R? This is a four key combo which should access the earliest macOS installer for your Mac. In fact many Macs will only boot to the earliest installer instead of the latest one. Maybe try a PRAM Reset, then immediately boot into Internet Recovery Mode using the four key method I described. To be doubly sure the NVRAM boot settings are clear you can also issue a command from the Terminal app:
sudo nvram -c
You will be prompted for your admin password. When you enter the password nothing will appear on the screen as you type. Press the "Return" key to submit the password. Reboot the Mac immediately after running this command and attempt to enter into Internet Recovery Mode using the four key combo.
And I don't want to install my OS from an USB but directly from Internet, and as I said, the internet option only proposes me the BETA version.
Why does it matter, unless of course you are unable to access the Startup Security Utility to allow booting from USB? At least with a bootable macOS USB installer if you happen to need to try reinstalling again it should go faster. The point is to reinstall an older version of macOS. I've already mentioned that Internet Recovery Mode doesn't always work as expected.
I have seen a couple posts on these forums with a command executed in the Terminal to tell macOS to use the standard macOS repository instead of the Beta tree, but I don't recall the command. It may be related to the "softwareupdate" command. However, I would not expect this to matter when booting from Internet Recovery Mode using the four key combo or from a USB installer.
