If the battery was flat,when you give it a run round and park it up again all you have done is put a surface charge in the battery. Try putting battery on a long slow charge.When you consider alternator output is roughly 75 amps and the battery is around 500amps cold cranking power you would need to drive for quite a long time.
You can also measure current drain on the battery with a digital amp meter.
To do this connect meter between battery positive and positive leads, make sure you actualy diconect all the positive leads and reconnect them all to one side of the meter as you want the current to flow through the meter.
Start by opening a door and see how many amps the courtsy light draws.
Any readings you have your not sure of take a fuse out one at a time until current draw stops and then you found your fault.