SOLUTION (I was on the phone with apple support for a half hour and they walked me through it) Hard shut-down your MacBook Turn on MacBook while holding option+command+R to enter recovery mode When prompted connect to Wifi, choose your language and log into your account It should prompt you with like six options. I first went into disc utility and ran first aid on all the internal drives (two for me). I don't think this is essential but may be a safe bet After running first aid select the option to reinstall Big Sur, it should be already downloaded and then will just reinstall This is what I did and everything is working fine, I waited about 8 hours with the installer stuck on 100%. Hope this helps!!