Troubleshoot a flashing folder at startup

HARDWARE PROBLEMS - FLASHING FOLDER WITH A QUESTION MARK
At startup, a flashing folder with question mark often indicates a failed hard drive, hard drive cable, or bootable operating system.

1. Turn off everything (including printers, etc.) and restart
   • Isolate if there has recently any change to equipment, and then go over connections, terminations, and power.
2. Turn off and unplug everything (including keyboard, mouse, & monitor) and restart
   • Check equipment for possible damaged connectors / pinds etc
   • Turn on equipment and add peripherals (50%)
3. Reset NVRAM / PRAM(instructions).
   • Power off your Mac.
   • Press your Mac’s power button and then immediately hold these four keys at the same time:
     ⌘ + option + P + R.
   • Continue holding the keys until your Mac restarts for the second time. On older Macs, the chime will sound upon restart. On newer Macs, the Apple logo will appear and then disappea
4. Restart the computer in safe mode (instructions).
   • Power off your Mac.
   • Press your Mac’s power button and then immediately press and hold left shift button as the computer turns on.
   • If your machine powers on at this point, it indicates there is an extension or application that may be causing the issue.
5. Boot in to recovery mode (instructions).
   • Power off your Mac.
   • Press your Mac’s power button and then immediately press and hold Command (⌘) + "R"
6. Click on Disk Utility
   • If no hard drive is discovered, you'll need to contact Apple Support for a repair option.
   • If a hard drive is present, proceed to the next step.
7. Run First Aid on the disk
   • If computer said it repaired something and the Macintosh HD appears to be OK, then re-run First Aid a second time.
   • If computer says the disk cannot be repaired, back up data, you'll need to contact Apple Support for a repair option.
8. If First Aid was successful, restart the computer
   • If the issue continues upon restart (Flashing Folder with Question mark), then return to recovery mode, and reinstall macOS on your computer.
   • If the issue continues (Flashing Folder with Question mark), after reinstalling macOS on your computer, then perform a clean install (ALL DATA WILL BE LOST)
     1. Click On Disk Utility
     2. Erase the Hard Drive
     3. Return to the utilties screen, then click on reinstall macOS
9. If issue continues, then a hardware repair is likely. Contact or visit an Apple Store or Apple repair specialist to fix your computer.