Help for my macbook on monterey

Recently I updated my macbook pro retina 15" mid 2012 from macOS Catlanina to Monterey. I took a 16GB usb stick and installed macOS Monterey on it and everything went fine. Now, when I try to boot from the stick, it boots and even gets notification sounds, but after I enter my password, it gets stuck on a progress bar with two thirds to go. I can see my profile picture and name, as well as the default Monterey wallpaper. The Macbook then gets really hot and nothing happens (I left it like that for several hours). I then booted the Mac into "safe mode". There I opened the open legacy patcher and tried to build and install open core, it then shows a warning that the disk failed to mount. What can I do now? Thanks in advance for your help.