You said the display so I take it the camera works just fine otherwise, ie being able to downnload pictures etc.
I would imagine the ribbon cable, the back light or the display itself is at fault.
Since it has a 'twistable' display I would imagine the cable harness to the display has been damaged with all the movement and stresses the cable suffers. If you imagine a very thin wire and you keep waggling it about it will soon fracture and break.
This is what *may* have happened - it did happen to my A650. I managed to repair myself by getting a complete new cable assembley, it is no easy task since you have to strip the camera and handle very tiny screws afterall, I am an electronics engineer .... a job certainly not for a novice so to speak.
By all means try a full reset in the menu, but I doubt that will cure the problem for the reasons given.
Best advice would be to seek a Canon repair agent near your locality.
Dave
