It looks like your Lumix's image sensor is acting up, since red/green/blue dot patterns are visible. Which would make perfect sense if the camera is old – no camera has a infinite life.

Sorry to hear. My suggestion would be to either take the malfunctioning camera to be fixed, or simply buy a new one. Buying a new one will likely be cheaper, plus you get a brand-new product instead of one which is "limping along".