1. Make sure the battery terminals are not dirty.
2. Make sure the batteries are in the correct way.
3. Make sure the battery is charged.
4. Make sure the battery cover is completely closed.
Memory Card Locked
1. Remove card from camera.
2. Ensure that the switch on the left hand side of the memory card is not in "locked" position.
Resources
http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_sd_series/powershot_sd600#ServiceAndSupport
http://www.easytechsupport.info/canon-cameras.php
