iATKOS | United Kingdom

I tried installing MacOS 15.7.3 on a 2011 IMac. This went as well as it could go until I started fumbling around with the EFI partition, as I wanted it to automatically boot into macOS instead of having to choose the Macintosh HD everytime it boots. Now when holding Alt/Option when booting, it first shows a white screen then only shows “Install macOS Sequoia” or it shows an installer, when I choose “install macOS sequoia” it goes into the recovery, where I can delete partitions and install like you would normally. If I choose the installer, there is a black apple screen with the loading bar that shows “xx minutes until finished”, well it doesn’t finish anything and reboots again. The same happens when I try to reinstall macOS Sequoia, it loads, then when it’s about 2/3 done, it reboots and I’m back at 0. Although it does not finish, it does install something. When I remove the usb stick, the Mac remains at the white screen. Also the fans go wild while doing any of this. So does anyone have any ideas what I can do?