in terms of your battery being flat, check the the alarm has been installed correctly, the alarm need to be installed on a power source\circut that will still allow the car to go into power save after 22 mins.
To check do this, when you next park the car , get out lock up as per normal using your newly installed alarm.
Take note that you will the the light on next the the "P" by the gear stick, after 22 mins the light should go off.
If not your alarm is installed incorrectly and will cause your battery to drain overnight or at least weak, same symptoms and a bad grounding. Hope that helps.