Had the same problem with my daughter's Samsung tablet. A black screen but I could hear the tablet "working" so it wasn't totally dead.
Watched this video on YouTube - https://www.youtube.com/watch?v=S-w3fP5bdT8
As per the video instructions I took the back off the tablet and reconnected the LCD connector. Clipped it back into place and hey presto the Tablet now works and displays normally.
I suspect my daughter may have dropped the unit causing the connector to come loose. Then again it may just work loose over time. Its a fiddly thing to reconnect but you should get it done in 5 mins. Just be careful taking the back off the tablet. Take your time and work your way around the edge slowly.
Hope this helps.