Power Outage during Vista update wont load Vista

My brother is having a problem with his computer, he did a windows update and the system restarted, the screen came up during restart that said installing update do not shut down computer and they then had a power outage. Since then my brother cannot get windows to load completely, it will get to just before the user login screen would appear and then restart or it just hangs indeffinately on the loading windows screen. He's tried loading in safe mode and using last known good configuration but they have the same result. Is there anything he can do to get Vista running again?

Any help is appreciated.

What if I don't hav ethe boot up vista disk?