Trade In Intel iMac: OS accidentally deleted

Thanks but there wasn't anything in the article that was useful. Thanks for sharing. I'm grateful for your time.

Thank you for your reply. Cmd-Option-R also fails. I'd gone to the trouble of creating a bootable Install Sonoma flash drive however the screen told me the Security settings wouldn't allow booting from an external, yet there's no longer a MaOS to use to change the setting.

Researching Apple Support online, and after Install from Internet failed via Wi-Fi, I took Apple's advice and attached an Ethernet cable to my router. This again failed.

I've reached the point where I guess I will just have to return it to Apple sans MacOS and take whatever hit I take to the trade in price. I'm vexed with myself for not finishing the initial article and botching things.

Yes, thank you. I created a bootable flash drive and the older (2017 Intel iMac) rejected it with a message that "this Mac's security setting" won't allow a bootable option. I appreciate your interest. I've tried all the suggestions on the Apple Support site.

Thank you for your time!

The keyboard is USB and functioned. The mouse is bluetooth but responded when presented with the WiFi login dropdown menu. The iMac got on my WiFi net but failed to download Sonoma via WiFi. Apple docs suggested Ethernet as a solution, which also failed to download. I don't see a solution here. I'm near an Apple Store and will take it to the Genius Bar if a 2017 iMac is still considered serviceable, which I doubt.

Thanks for your help. I can't reinstall the OS. Recovery has failed with a USB flash drive of "Install Sonoma" and via the Internet. The Mac is going back to Apple for a trade in, not a new owner. I'm just going to take the hit and return it.