Hi,
Can you take a picture and download it to a computer to check if the image is OK? I realize that you cannot "see" what you are taking.
If the downloaded image is just a black image then there may be a problem with the CCD sensor or sensor connection to the motherboard.
If the downloaded image is OK then there is a problem transferring the image from the sensor to the camera's LCD screen.
Here's a link to a [https://www.youtube.com/watch?v=WI4N7vrnMdU|video] that shows how to dis-assemble the camera.
I know it's not for your particular fault but it still may be of some help in gaining access to the components of the camera.