Hi guys. I've made a copy of osx to an external hdd. Taken out the old in my mbp and put the new Samsung ssd in. Started up the laptop and I just get a white screen with a flashing folder with a question mark. I thought it would be possible to install osx from the external hdd. Is there some settings I need to change before installing the ssd that I havent changed? First time doing this and YouTube videos don't really offer much help.