Another quick method:
: If a download fails within 3uTools, you can manually download the file from sites like IPSW.me and use the Import button in the Flash & JB tab to select it from your computer. 3utools ipsw location top
Look at the top navigation bar and select (or Go to Firmware depending on your specific version). Another quick method: : If a download fails
Users/<UserName>/Library/iTunes/iPhone Software Updates/ /Library/iTunes/iPhone Software Updates/