Forgive me is this is listed somewhere, "Search..." did not retrieve any threads.

I have a Mac Classic II which had a PRAM battery leak all over the place killing my motherboard.  I have successfully found a good motherboard from another Mac Classic II which I've put into my computer.  The computer boots to a screen w/ a folder w/ a "?" inside it.  I've installed system 7 from floppy with success.  However when I go to re-boot my computer I get the folder with the "?" inside it again.  

Any help would be appreciated!