The Nokia 5610 XpressMusic has to have the back cover (battery cover) attached, for the phone to recognize the memory card. There is a button close to the memory card door which must be depressed for the phone to access the memory card. This button is depressed when the back cover is attached.
* WARNING: Use only batteries, chargers, and enhancements approved by Nokia for use with this particular model. The use of any other types may invalidate any approval or warranty, and may be dangerous.