I know nothing about cars
and today i tried to start my mini, i turned the key, turned off the immobilser then turned the key all the way and the engine tried to turn over but it wouldnt 
i rang my machanic and he said he thinks it is the battery.....but i didnt leave any lights on or anything
what else could i be?
thanks x
It could by all means be your battery. There's loat of things it could be.
- Battery
- Points, Condenser, Distributor (could have stopped working due to water damage)
- Starter Motor/ Solenoid
Did the starter motor turn over okay or was it turning slowly? If so it's the battery or a bad starter motor..