so basically, my macbook pro was run over. the only thing broken, as far as i can tell, is the hdd and the screen. so what i am trying to do is connect a new hdd and external screen, and install os x again. my problem is, that the external screen isnt working. i cant get it to show any boot up actions. is this because there is no os installed, and it doesnt know how to configure the screen? i have a cd to boot to, but would still like some advice or suggestions. thanks in advance.