Remove the battery from your camera and replace it once it is fully charged or buy a new battery if your current one is over a year old. See Battery Removal for more details.

Once the battery is out, remove the memory card from camera as well. See Memory Card Replacement for more details.

Turning the camera on without a memory card will reset the camera. If the camera has been reset and displays a memory card error message, then the memory card can be reinserted and the camera turned on once again.