I have a 2011 Mazda3 i Sport that was purchased in October. I just came back from a 3 day trip. My Mazda was kept in our garage while we were gone. When I came back and tried to start it up, I got nothing. No sounds and only the passenger airbag light came on. Then the gauges started moving back and forth several times. This happened whether the key was in or out of the ignition. We had to override the gearshift in order to get it into neutral so that we could get it out of the garage and try to jumpstart it (per the service department at the dealerships directions) and we still got nothing. The gauges started moving again after attempting to start it. Eventually we had to have it towed in to the dealership and are waiting for service (happened over the weekend after dealership has closed). Has anyone ever experienced this problem? No lights were left on, all power was off and nothing was plugged in to the accessory ports (like a phone charger or mp3 aux cord). I find it a little weird that a new car with less than 4k miles on it would be acting like this. It's not driven hard at all and since it was purchased we have only used it once or twice a week.

 

Is there any evidence of someone breaking into the garage... if the battery wasn't the issue i'm wondering if someone tried to steal it and caused this issue.
You may want to try a hard battery reset as well - disconnect for a few minutes to see if it resets anything.

 

That was the first thing I checked for and it didn't seem like anyone tried to break in. I got it back from the dealership and they said that they didn't know why but that the battery was drained. They charged it, drove the car for 10 miles, and checked the battery and it tested fine. We still have no clue what happened. We don't drive the car much and when we do it isn't for very long. I have been reading that this alone can sometimes deplete the battery's charge. Maybe that's what happened. Anyway, all seems fine now but I'm still going to keep an eye on it and maybe take it for an extra trip once a week to keep it charged.

 

Instead of using gas, you can get a trickle charger to keep the battery topped up so to speak. As an experiment, you can let the car sit for a few days at a time, then get in and make sure the ignition turns on or something simple like that. The battery should last a few weeks before draining, if it doesn't there's an electrical drain that shouldn't be there, and you can have the dealer investigate.
Glad it seems to be ok at least.

 

Did you have anything plugged into the either of the outlets (the one on the dash and/or the one in the armrest). Reason why I ask is because I noticed that they supply power all the time. I had my phone charger plugged into the armrest outlet and noticed the light was glowing on it one night. The car was off and no key in it. Then, I plugged my phone in to make sure it wasn't just "residual" power of some sort. Nope, the phone started charging. A few days later, I noticed the charger quit charging my phone and the charger was REALLY hot from it constantly being plugged into juice. Basically, it got burnt out. Something like this running non-stop for 3 days could possibly drain the car battery. Bad design idea from Mazda in my opinion. Food for thought to consider. Not sure why Mazda would do that. At the least, it kills car cell phone chargers and at the worst could cause one to get a tow.