Carbon monoxide alarm help ?

laying in my bed for about 30 min then this daft carbon monoxide alarm started bleeping so I checked it to maybe change the battery's but says I can't open it coz once the lids closed it can't be open ,I've timed this bleep bleep to every 58 2nds any one know why it's bleeping bcoz the thing well not shut up and I can still hear it even know I've stuck it in the middle of the washing basket