How can I fix my Lumix DMC-FX33?

Make & Model: Panasonic Lumix DMC-FX33

Problem
The camera can still playback and record Motion pictures, but fails to take normal pictures. It still focuses, but doesn't take a picture and eventually a message appears:
PLEASE TURN THE CAMERA OFF AND THEN ON AGAIN.
After following this instruction it still doesn't take pictures.
We recently had to purchase a battery charger, but it's not from Panasonic for this camera.
My son has used it on a school trip and thinks it might have become slightly wet.