If your Mac has no signs of power, start by making sure that it's receiving power:
- Make sure that your power cable is undamaged and securely plugged into your Mac and a working electrical outlet. If you're not sure about the outlet, test it with a lamp or other device.
- If you're using a Mac notebook, make sure that it's using the correct power cable and adapter, and that it has been plugged in for about 5 minutes, which is long enough to provide a usable battery charge. Learn how to troubleshoot USB-C power adapters or MagSafe power adapters.
- If you're using an external display, make sure that it's turned on, securely connected to your Mac, and isn't experiencing any video or display issues.
Then try these solutions, whether or not your Mac has signs of power:
- Press and hold the power button on your Mac for 10 seconds, then press it again.
- Reset the System Management Controller (SMC).
- Make sure that your display's brightness is turned up. Mac notebook computers have a Brightness Up
key on the built-in keyboard. - Unplug all accessories from your Mac, including printers, drives, USB hubs, and mobile devices. (You could have an issue with one or more of those devices or their cables.) Once more, press and hold the power button for 10 seconds, then press it again.
If your Mac has signs of power but the screen remains blank, try the steps for when your Mac starts up to a blank screen.
If you still need help, please contact Apple Support.
Source ➔ Apple Support Document.
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