If a valid loader is found, your Mac will display the Apple logo. If no bootable-drive is found, or the bootable-drive found does not have a working loader, your Mac will display a flashing folder with question mark.
Your Mac will chime after passing the test, then search for a “loader' from the available bootable-devices such as hard drives, optical drives or USB drives. When you turn on the Mac, the CPU will perform a task named “Power On Self Test”. In order to quickly diagnose and fix the mac question mark folder issues for your MacBook, iMac, Mac Mini and Mac Pro, you need to understand how an Apple Mac loads the macOS from the hard drive.
