When your iMac Pro starts after being turned off, the display might remain dark for up to 30 seconds before the Apple logo and progress bar appear. This is expected behavior. Don't press the power button or unplug your iMac Pro during this time.
Also, when your iMac Pro installs operating system updates, the Apple logo and progress bar might appear, and then the display might go dark. The display can remain dark for 45 seconds to a minute as the installation progresses. Depending on the updates, your iMac Pro might also restart during the process.
Avoid iMac Pro startup issues
Don't unplug your iMac Pro or press its power button while it starts up or installs updates.
More iMac Pro startup tips:
- Avoid pressing the power button at the same time that you connect the power cord to the back of your iMac Pro. The power button is on the left-hand side when iMac Pro is facing you, so try holding the computer at its bottom-right corner while you plug it in so you don't press the power button accidentally.
- After you connect your iMac Pro to power, wait a few seconds before you press the power button.
- Wait a few seconds after you shut down your iMac Pro before you press the power button to turn it back on.