2012 iMac Not Booting

[pspork2]

I hadn't used our 2012 27" iMac in some time, and it was off. I turned on, got the chimes, and a loading bar started. The loading gets almost to the end and the computer turns off or just goes to a black screen. Does anyone know what these symptoms may reflect?

Also, is there a place for instructions on different ways to attempt to boot this machine and gain access to any files that are still there? I tried a few things I found on forums previously without any luck. Can confirm that the keyboard still works (all peripherals are wireless).

I did order a new M1 iMac that comes in a week or two. I do not have a more current machine running MacOS in my household.

Thanks for your help.

 

[rpmurray]

Have you tried booting into Safe Mode or Recovery? Mac startup key combinations

 

[pspork2]

@rpmurray I'm not sure. I will try again and report back. Thanks for that link. It is very helpful!

 

[Fishrrman]

It sounds like it could be a failed graphics card or a power supply.

As mentioned above, try a safe boot (boot with shift key down).

Something to try:
1. press the power-on button
2. IMMEDIATELY hold down the "T" key
3. Do you get "a floating icon" on the screen?
4. If you DO, this is "target disk mode". I think you need a thunderbolt2 cable to connect it to another Mac. Then you can access the internal drive with another computer.

See this URL:

Target disk mode iMac 2012 - Apple Community

discussions.apple.com