problem el capitan during installation
i try to install it with a usb, with a update from mac app store, but everytime the installation block on the status bar at beginning ( after reboot). I speak with apple support in chat but they can't solve the problem ( NdR). So, can i do now? Actually i reinstalled yosemite after two inizialitations
MacBook Pro with Retina display, OS X Yosemite (10.10.3)