imac M1 2021 screen dead: how do hook up to external?

Question

Level 1

9 points

imac M1 2021 screen dead: how do hook up to external?

I have an M1 2021 imac where the screen flickered/ lines and now will not display.

I am getting an M4 but need boot up the M1 imac and get some info off it.

I have an external monitor (HDMI) and a USBc thunderbolt 3/4 to HDMI cable...this did not work. When I turn on the dead screen m1 imac I hear the chime and can can tell barely that if there was a working monitor I could see the info. I tried safe mode but it did not work either. No display on extenal.

How do I get the external monitor or even another imac ( I also have a 27" imac; which I haven't tried to do this on yet as I don't know how to do it) to show what is on the m1 imac?

thanks

Posted on Jul 28, 2025 9:09 AM

Reply

Answer 1

Jul 28, 2025 10:29 AM in response to kroes

You might be able to put the 24” iMac into the equivalent of Target Disk Mode.

Transfer files between a Mac with Apple silicon and another Mac - Apple Support

Reply

Answer 2

kroes Author

Level 1

9 points

Jul 28, 2025 6:20 PM in response to Phil0124

I used a different cable than a USBC to HDMI. I went with a usbc to display port cable and then applied your idea of the command +F1 and it mirrored and WORKED.

Thanks for the help!

Reply

Answer 3

Phil0124

Level 10

216,308 points

Jul 28, 2025 10:25 AM in response to kroes

kroes wrote:

I have an external monitor (HDMI) and a USBc thunderbolt 3/4 to HDMI cable...this did not work.

Meaning?

What happened when you plugged in the external monitor?

Did it remain black and show no signal or did something else appear?

If you see your desktop, but nothing on it, you can press command+f1, or command+fn+f1 to switch between extended and mirrored modes.

If you see nothing but a black screen, then the external display is not being correctly detected or does not support the provided resolution, which would require you navigate the iMac to fix that.

You will not be able to use the 27" iMac as a display for the M1 iMac though.

Reply

Answer 4

Jul 31, 2025 4:11 PM in response to kroes

M4 iMacs might have the same problem with the display.. perhaps think about an Mac Mini, if the M4 shares the same design as the M1, the display could fail out of the blue.

Reply

Answer 5

Phil0124

Level 10

216,308 points

Aug 1, 2025 12:28 PM in response to kroes

Welcome, glad it worked.

Reply