Mac has blinking folder with? In it and will not power off no matter what I do

If your Mac starts up to a question mark says

A folder with a flashing question mark means that your startup disk is no longer available or doesn't contain a working Mac operating system.

If the question mark appears only momentarily before your Mac starts up normally:

1. Reset NVRAM.
2. Make sure that your preferred startup disk is selected in Startup Disk preferences.

If the question mark persists, follow these steps:

1. Press and hold the power button on your Mac for up to 10 seconds, until your Mac turns off.
2. Turn on your Mac and immediately press and hold Command (⌘) and R to start up from macOS Recovery.
3. While in macOS Recovery, use Disk Utility to repair your startup disk.
4. If Disk Utility found no errors or repaired all errors, reinstall macOS.
5. If you still need help, please contact Apple Support

To force restart your notebook follow the instruction in Shut down or restart your Mac:

You can force a shutdown if necessary — for example, if your Mac becomes unresponsive — by pressing and holding the power button until your Mac shuts down. You may lose unsaved changes in open documents.

For the "folder with a question mark," the support article you came here from should provide you with the steps needed to try to

resolve this issue. Have you tried them all yet? If so, and they didn't help, I suggest that you contact Apple Support directly. To do so, simply select the "Get Support" link in the upper right-hand side of this forum's web page.

For the power-down issue, it would help if you can provide us with what exact model is your Mac Pro?