Follow these troubleshooting steps if a Mac is experiencing errors which may be due to a hardware failure.

https://support.apple.com/en-us/102550

Apple silicon

Press and hold the power button on your Mac. (Every Mac has a power button. On laptop computers that have Touch ID, press and hold Touch ID.)

As you continue to hold the power button, your Mac turns on and loads startup options. When you see Options, release the power button.

Press and hold Command (⌘)-D on your keyboard.

Intel processor

Turn on your Mac, then immediately press and hold the D key on your keyboard as your Mac starts up.

Release when you see a progress bar or you're asked to choose a language.

If using the D key doesn't work, press and hold Option (⌥)-D at startup instead. If neither method works, review the guidelines for using key combinations at startup.