Provided it is not that EVF is selected, or lens cover is on, it could be:
- screen broken
- screen connector malfunction
In the first case it could be caused by a drop or similar. You should see evidences of broken screen on glass. In this case it should be replaced.
You should disassemble the LCD.
Follow disassembly guide but just step 18, no need to teardown the whole camera.
On the second case it could be caused by humidity or water, or even a drop that has moved flex cable from its connector.
You should disassemble the LCD and inspect it.
Follow disassembly guide but just step 18, no need to teardown the whole camera in the first place.
Remove LCD and adhesive tape. Clean every connector and component with isopropyl alcohol and a toothbrush. I managed to revive my LCD that was only showing white light and some stripes.
With LCD in place, test voltage on slim power connector/flex cable. On my camera it registers some 15.30V
If voltage is ok and LCD is not lighting up (some white light) it should be replaced. If LCD is lighting up but showing ghost image or stripes, video connector should be cleaned.
If no voltage is registered, you'll have to disassemble the back of the camera and inspect flex cable and connector from mainboard. And clean and replace if needed.