Electrical Problem

I hit the ignition switch while my 2001 Honda Prelude was already started and now my battery keeps going dead. I've replaced the battery and it ran fine for 2 weeks and now it died on me again. When I turn on the ignition switch all my lights, displays and such come on but it doesn't start. I just had a new alternator put in prior to my trying to start the already running car. I did smell something burning but the car ran fine until I cut it off, then it wouldn't start which is why I got the first new battery.