A. When you use the firmware update method to load your camera with CHDK, it doesn’t actually change the firmware. Because it is just a memory-resident program, it only remains in the camera’s memory until the camera is turned off. You need to reload CHDK each time you start your camera. If something goes wrong and camera does not respond, you only need to switch the camera off or remove the battery (and perhaps delete CHDK from the memory card) to return to the original firmware. Note : CHDK also has the ability to autoload (see the next answer). If you remove the memory card containing CHDK or disable the “SD Card Lock”, CHDK will no longer load the next time you start your camera.