Hey, I have a 5K iMac which was running OS X El Capitan and Windows 7 (Bootcamp). I upgraded yesterday to macOS Sierra and now I can't boot into Windows 7. It keeps restarting and want's to start the repair assistant. When I try to launch the repair assistant, I can't do so because my keyboard and mouse won't react. I can't move the mouse or type anything. Any ideas how I can get Windows up and running again? Thanks!