Question mark folder at startup when downloading Sequoia onto 2013 iMac???

I downloaded sequoia onto my late 2013 iMac with Open Core Legacy Patcher and everything went good up until the very last part. I finished installing everything and I got up to the part where it was updating to the new macOS (sequoia). For a while there was an Apple logo with a loading bar, and then two images popped up but it chose automatically and started loading with the Apple bar again, and then after that was finished loading this flashing image of a question mark file came up? I thought I followed everything in the YouTube tutorial and I was literally at the end, can someone please help me fix this!! I would appreciate it a lot