Windows Update Error Code 8007065E

I am using Windows 7 Home Premium on a 64 bit operating system. I haven't used this computer in over a year, but my brother has been using it since, but hasn't kept it updated at all or with any anti-virus. I was able to install everything on Windows Update except Security Update for Windows 7 for x64-based Systems (KB2621440). I've tried everything from simply restarting, rebooting in safe mode and safe mode with networking (I could not open windows update either of those ways), and doing a safe mode with networking full scan with Malewarebytes Anti-Malware, Super Anti Spyware, and Microsoft Security Essentials. I did find 2 trojans and removed them and rebooted, but was unable to install this security pack still. When I tried installing the individual version of the security pack online, it told me the update did not apply to this system. I also tried running the windows update repair tool. I made a separate administrator account and downgraded my own account to a standard user, but I'm unable to demote my brother's administrator account. His is not password protected, but there is no option to change the account type, even when I'm logged on as him or under the other administrator account I just made.