[Spridgets] No LBC - Miata question

[Nory]

I know some of you have Miatas, so maybe you can answer a question  
for me.

A friend of mine couldn't get her Miata started, so we thought the  
battery was dead (it's been sleeping in the garage for a while).   
After charging the battery, the headlights work, but nothing else.   
It looks like the main fuse is out.  It looks pretty easy to replace  
(am I right????), but we were wondering what may have caused the fuse  
to blow.  Does she have another issue going on that might be a  
problem?  Is there anything I need to know before replacing the fuse?

Thanks!

-Nory