Chosen Solution
i will use startup manager for booting with usb device but ALT ( Option) doesn’t work at starting up, i search solve in google i find to reset NVRAM with “CMD + Option +P+R” This command doesn’t work too because ALT ( Option) not working for any Command have this button ALT (Option) Work in OS but at starting up not working please help me!! I disable SIP and i Enable it and no result.
Are you holding alt 100% of the time before and after pressing the power button until the boot selection menu displays? It may take around 10-30 secs while holding alt. Depending on which OS was installed some may take longer to show it when trying to get to the EFI boot menu.
