Reset the NVRAM / PRAM

rusty.john51 wrote:

I followed the procedure to reset the NVRAM / PRAM and the Mac will not restart. It's making a low pitch beeping noise (beep-beep-beep-pause- - repeat). What do I need to do?

If your Mac doesn't turn on

https://support.apple.com/en-us/HT204267

If your Mac doesn't start up all the way

https://support.apple.com/en-us/HT204156


If your Mac starts up to an Apple logo or progress bar

https://support.apple.com/en-us/HT207019

Learn about the sounds your Mac might make when it starts up and what these sounds mean.

Mac models from early 2016 and earlier make a chime

sound when they start up. Mac models from late 2016 and newer don't have

a startup chime, with the exception of MacBook Air (13-inch, 2017).

If there's an issue with your Mac, it might make one of these tones when it starts up:

• • One tone, repeating every five seconds: No RAM is
  • installed. If you recently replaced or upgraded your computer's RAM,
  • check to see if it was installed properly. If the issue continues, contact Apple Support.
  • Three successive tones, then a five-second pause (repeating):
  • RAM doesn't pass a data integrity check. If you recently replaced or
  • upgraded your computer's RAM, check to see if it was installed properly.
  • If the issue continues, contact Apple Support.
  • One long tone while you hold down the power button: An EFI ROM update is in progress. This applies to Mac computers from before 2012.
  • Three long tones, three short tones, three long tones:
  • EFI ROM corruption is detected, and your Mac is in EFI ROM recovery
  • mode. Newer computers automatically recover from a corrupted ROM; when
  • this occurs, a progress bar appears on the screen during ROM recovery
  • mode. Don't disturb your Mac while the ROM recovery takes place. When
  • recovery is complete, your Mac restarts.

About Mac startup tones - Apple Support