Nissan Repair: Battery reversal on a Nissan 300zx, nissan 300zx, fuel pump relay

Question
My friend installed a new battery in her 86 300zx and smoke came out by the battery. Now the car will start for a few seconds and then die (im guessing this is the cold start circuit functioning)
She checked for bad fuses and found none. Other symptoms are no talking computer.

So whats the best guess, blown computer, alternator and what else? Is there more than one computer module that must function for a running engine.

Thanks for any help

Answer
James,

If the battery was reversed there are many systems that can be cooked.  I would first start with the fuses and fuse links at the battery.  Then, get a test light and see what is going on when the car runs for a few sesonds and then dies.  I would be checking the fuel pump relay and possibly the computer.  But, first, check all the fuses.  Also, you were right on with the alternator getting toasted too.  Just a matter of diagnosing one system at a time.