resetting using Macintosh hd get error

Start up from macOS Recovery

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

In Disk Utility>View, select Show all Devices, highlight the top left entry.

Run Disk First Aid on every listing on the left.

APFS won't work for Sierra or earlier, Sierra or earlier needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.

If all else fails...

https://mrmacintosh.com/how-to-fix-the-recovery-server-could-not-be-contacted-error-high-sierra-recovery-is-still-online-but-broken/

Use http:// instead of https://

https://www.youtube.com/watch?v=ouNQS36dIBw&t=95s

The formula for caos: APFS+macOS High+EFI… - Apple Community

MacOS High Sierra Problem - Apple Community

Hey there!

What’s the year of your iMac? To check, find the serial number printed on the underside of your Mac, near the regulatory markings. It’s also on the original packaging, next to a barcode label. You can then enter that serial number on the Check Coverage page.

-Jack