Sorry to hear about your frustration. I am confident that the reason you are unable to install your operating system is because the installer became corrupted during download. This is a common problem with a wireless download of such a large file. Put the installer into the trash and do another download. You say that you were using Wi-Fi to do the download. Don't. It's too much data for Wi-Fi. Instead, you need to use an Ethernet cable directly connected to your modem/router. If necessary, temporarily move your computer to do the download. And during the process, stay off the internet. If you are unable to directly connect to the internet, then be prepared to do multiple Wi-Fi downloads until you get a good one that loads. And allow each download to fully complete, which can take up to an hour, more or less, plus another 45 minutes or so for the installation. And don't use the internet during the download. Good luck. I hope it goes well.