If your Mac won’t turn on, and you instead hear beep sounds, there may be a hardware issue. Whenever you turn on your Mac, it will run diagnostic tests, and if one of those tests fails, you’ll hear beeps. Here is what those beeps mean.
- One repeating single beep with a 5 second delay.
This means that no RAM was found – the memory is either not installed, is damaged or is not correctly seated in the RAM slots.
- Three repeating beeps, with a 5 second delay between them.
This means that RAM was found, but it failed to pass an integrity check and may be faulty, or the wrong type of RAM for the computer.
- Three long beeps, then three short beeps, then three long beeps again.
This means that the EFI ROM has been corrupted, and the Mac is in EFI recovery mode. It will restart automatically when the EFI recovery is complete.
- One long beep as the power button is pressed
This means that an EFI firmware upgrade is in progress. You should allow it to complete.