iATKOS | United Kingdom

Hello everyone, I’ve been trying to install at least Big Sur on an iMac I received recently for fun, but every time I click on the EFI boot, it starts to load the “install macOS Big Sur option” with the pressed number at the bottom, before rebooting back into high sierra. There’s a separate issue where the iMac just boots slow in general despite having having an SSD and 12 gbs of ram. I doubt the i3 it has would be giving this much of a headache either. I’ve tried everything such as resetting nvram/pram, reinstalling macOS and rebuilding and installing open core as well, I tried the same with Sonoma, Monterey and more, but nothing has happened Thanks for any help