both internal and external screens not working

[jayyoungdesign]

I have an iMac 24 M1 2021. The internal monitor is failing. I have installed your software trying to turn off the internal and run with an external monitor. I currently cannot get either internal or external screens to show, meaning I am not able to login and get running. I have tried holding the power button to get startup options but still nothing. Please help get me back so I can at least see the internal screen again to login.

[waydabber]

Disconnecting the built-in display on an iMac (for which you need to turn off the safety regarding this with the explicit warning) is a runtime event, not something permanent and certainly does not affect the boot environment. Additionally, even if the built-in screen is somehow stuck disabled, upon successful boot an external display should still connect.

Do you hear a bootup chime (if configured) or see the screen backlight on or anything happening or any indication that the Mac does something, or does it behave like a brick? If not and you are sure that the system has power, then as a last resort you can try restoring the Mac: https://support.apple.com/en-us/108900.

[waydabber]

Note: I see this is related to #5697