cannot connect my battery without my alarm going off. how do i turn it off?

i took my battary out to charge it when i put it back in the alarm goes off. its a bmw 316i se 97 r reg. i have tryed the key fob but it does not even open or close the doors when the battary is connected. i have even tryed closing the bonnet and using the key in the door. but as soon as i open the door it goes off again and i have tryed in ignition but its off again. what do i do to reset it