I have a Mazda 3 Takara, 5 door, from 2009 (I'm in the UK if that matters).

The battery is flat. Before this, the alarm was on.

My assumption is that, ordinarily, if I open the door with the key, the alarm will go off.

However, with a completely flat battery it won't.

But ... does my car have one of those back-up batteries for the alarm, so that it will go off after all? If so, what do I do? I need to open the door to open the bonnet (hood) to charge the battery, and I can't inflict an alarm on my neighbours for however long it takes to get enough charge in the battery to turn off the alarm. (Btw, it's not the fob battery - the car didn't start, I left it a few days through being busy, went back and the fob still lights, but the doors don't open.)

Any info/advice gratefully received!

Thanks,

Paul