Nerdcore Australia
Feb 7, 20221 min
Updated: Feb 26, 2022
If your iMac doesn't seem to turn on after you've pressed the power button, follow these steps.
Force your iMac to turn off and back on
Your Mac may be turned on but appear to be turned off, even though it's connected to AC power and a working display. Follow these steps.
Press and hold the power button on your Mac for at least 10 seconds, then release it. If your Mac is turned on, this will force it to turn off.
If you haven't seen a change on your Mac, press and release the power button.
If your Mac now turns on but stops at some other screen during startup, follow the steps for when your Mac doesn't start up all the way.
Revive the firmware, if applicable
If you're using a Mac with Apple silicon or a Mac with the Apple T2 Security Chip, in rare circumstances the firmware stored in your computer's memory might need to be revived or restored. To do that, you need these items:
Another Mac with macOS Catalina 10.15.6 or later and the latest Apple Configurator app, available free of charge from the App Store.
A USB-C to USB-C cable or USB-A to USB-C cable to connect the computers to each other. The cable must support both power and data. Thunderbolt 3 cables aren’t supported.
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