Yer.
Basically, I suspect you are using the 'update' file which is the big download box they have on the update page. however if you scroll down to the bottom of the page you will see a tab saying full instillation drop down menu. In there is a hyperlink (labelled Download). thats the one you want following the file set up instructions. (its around 800MB)
This will however completely format and install a new OS copy though so it will be like it was when you opened it -unfortunately the sudden power outs seem to of caused a OS file corruption so in this case its all you can do. You can ofc re log in to your account and any purchases you made will be in your library, but installs and downloads will need to be re done.