The computer chimes, and when I press any key like the option or R keys to enter recovery or the Startup Disk Manager, nothing happens. I tried to reset the SMC to no avail.

I have a 3TB portable HDD with a bootable install partition of Sierra I would like to install on the SSD.

2 Answers 2


Fixed it. The DisplayPort connector came undone.


Older Macs had what's called Parameter RAM (PRAM), newer Macs use Non-Volatile Random-Access Memory (NVRAM). Resetting this would be the first thing I'd do:

  1. Power off your iMac
  2. Press the power button and then press the commandoptionpr keys. You have to make sure you press these keys before the gray screen appears or it won’t work.
  3. Hold those keys down until your Mac reboots again and you here the startup chime.
  4. Let go of the keys and let your Mac reboot normally. In your case it probably won't boot normally, but then power off again and try starting up again with the Option key down to see if Startup Disk Manager appears.

Let us know how you go.

  • I reset the PRAM, but the screen is still black when I press the [option] key. Could it be a problem with the screen connector? Commented Feb 7, 2017 at 22:44

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