total dead end

[ian87w]

You need the Apple ID and password that the previous owner used, because it sounds like the Mac is still tied to his Apple ID. He needs to remove the activation lock from the Mac by properly signing out of the Mac (signing out of messages, FaceTime and Apple ID). Once he does that for you, you should be able to set up the Mac properly.

I don’t think activation lock applies here. Activation lock is only available on Macs with a T2 chip or M1. A 2008 Mac won’t have that.

 

[Apple_Robert]

I don’t think activation lock applies here. Activation lock is only available on Macs with a T2 chip or M1. A 2008 Mac won’t have that.

I was really talking about the Apple ID account information, even though I used the wrong terminology for the given year.

 

[ian87w]

so how would i be able to make a bootable backup if the only screen i can get to is the disc utility , sorry for the questions but i dont have a clue with macs ,

To the OP.
Since it’s an old Mac, I would think that it’s also probable that the hard drive is old and is dying. So if you are adventurous, I would consider replacing the drive sooner or later for any computer that old.

If you have another Mac, download a full macOS on that Mac and create a bootable USB drive. I’m guessing for a 2008 iMac, the latest supported OS is El Capitan.

How to download and install macOS - Apple Support

Download and install current or previous versions of the Mac operating system on compatible Mac computers.

support.apple.com

How to create bootable USB or macOS https://support.apple.com/en-us/HT201372

After that, simply boot to that USB drive on the iMac and erase the internal drive, and fresh install macOS.

This is what I did on my 2012 mini. I was never asked for any Apple ID during the fresh install.

 

[wys]

I have been in similar situations to OP, and these things helped;

Call Apple. Like, on the phone. When I had free old Mac's gifted to me, I had the exact same issues, and I just gave Apple a call, they ended up being extremely helpful and got me through the process of setting up the old Mac, even gave me several follow-up calls to make sure everything was working still.

As mentioned, create a bootable USB flash drive or bootable external USB hard drive to re-install an operating system from. I have used this program in the past to help me download older versions of macOS / OS X that were no longer available on the App Store;

GitHub - corpnewt/gibMacOS: Py2/py3 script that can download macOS components direct from Apple

Py2/py3 script that can download macOS components direct from Apple - corpnewt/gibMacOS

github.com

gibMacOS Tutorial ~ How to Download macOS Directly from Apple

When your Mac is ineligible to download Catalina or Newer macOS versions If your Intel Mac is from approximately 2011/12 or older (see post #2) you won't be able to download Catalina from the Mac App Store. Follow the instructions in these videos to enable the download of Catalina or newer...

www.tonymacx86.com

if that doesn't work, you might try some of these links; https://gist.github.com/0xmachos/e478f81525619d69aea64851705e0635
(I havent used these)

Once you get ahold of the installers for these old OS's, you can try to use the official methods to create a bootable installer;

Create a bootable installer for macOS - Apple Support

You can use a USB flash drive or other secondary volume as a startup disk from which to install the Mac operating system. These steps are primarily for system administrators and other experienced users who are familiar with entering commands in Terminal.

support.apple.com

Others mentioned buying a USB from eBay with the installers on them; not sure I would trust this one as long as you can still just download it yourself...