So I tried banging it and clearing the memory card which didn't work for me. The thing that did solve my problem was to clean out the cable ports inside the waterproof battery/card chamber. After reading the manual I realised that when a cable is plugged in to display your photos on a TV, the screen goes black. So I cleaned the cable ports with a toothpick and it solved the problem. Something must have got in there and closed a circuit making the camera think it was plugged into a tv. Hope this helps someone!