When the bottom componets are exposed, the battery is held by a blue latch. (Blue latch is circled in the picture)

Push the blue latch latch to relase the battery from its slot. It should be pushed out.

Remove the battery.

Move the blue latch to put in the new battery.

Make sure that the battery is going in the correct way. The three golden slits should be matching up with three golden prongs on the bottom of the battery holder.

Close the latch door over the components and move the latch toward the side of the camera. Trying turning on the camera.