Nissan Repair: 2000 maxima cranks wont start, loud pop, question thanks

Question
QUESTION: My 2000 maxima would start fine but die in cold weather.  After driving a bit it would work fine even if left in the cold for 8 hours to cool off.  Problem only occured when left overnight.  I started car and drove a few minutes and turned it stopped engine but left radio on.  Battery got too low and would not start.  Tried to jump car and it will crank but not start.  After attempting to crank a bit I heard a loud pop but same issue cranks but no start.  I can hear fuel pump turn on when I turn car to on but have no way to check pressure or compression.  No obdII codes triggering.  I know this is not a lot to go on but do you have any ideas as to what my issue may be?

ANSWER: Dallas,

The car backfired.  That was the loud sound.  I would say replace the battery and you should be back in the land of the living.  Email me back if a replacement battery does not do the trick.  I know the crank and crank part with a jump.  But, the battery is stealing any excess voltage.  Also, since it was jumped check the master fuses to make sure none have popped.  The ones at the positive terminal as well as the ignition fuse under the dash.

---------- FOLLOW-UP ----------

QUESTION: Thanks for the response.  I replaced the battery and I pulled the 2 main fuses and battery positive terminal fuse and they appear to be intact.  I got some starting fluid and sprayed it through the air intake with the throttle held open.  I know I should have taken hoses off to avoid damaging the MAF but it was below freezing and the hoses were uncooperative.  It did seem to run off the spray for a second so I am thinking fuel pump even though I hear it come on.  Changing the fuel pump looks easy enough but I really am a but over my head at this point when it comes to making sure that is the right thing to do.  There is only so much researching all of this online can do for me.  I also heard really unhealthy metalic noises from the engine when starting it from the starting fluid and am just hoping that is to be expected due to method of starting it.  I also have an probably irrational fear I will find out it is the nissan security stuff as I don't know if there is any easy way to check if the battery dying caused loss of key programming or something.

Answer
Dallas,

you will need to check the fuel pressure first.  Get an adapter kit from the store since they (Nissan) eliminated the pressure port to check fuel pressure.  If there is no pressure it is just a matter of removing the back seat and doing the change.  If the pressure is there you need to check and see if the key needs reprogrammed.  Check your other keys to see if they will start the car.  The fuel pump relay does not activate when the key is not read correctly or someone is trying to jack your car...