It can be also a flex cable or flex cable connector problem. So check them before buy replacment display. Some times flex just slides a litle bit out from connector causes problem like this. If a tablet was droped or bended than lcd control board and lcd connection flex can be damaged or lcd glass edge cracks causing the problem. This you can not see from outside or just removing back. Anyway in this case you need new display assembly which comes glued with midle frame and home button, so just move board and other staf from old to new and that it. Do not buy just display without frame from china guys because the price is almost the same and you will need to glue it with frame in correct position. One mistake can damage new display.
This part comes from home button and touch buttons location. Your tablet will work without it. You can see it in this Picture: https://d3nevzfk7ii3be.cloudfront.net/ig... Left side under plastic housing close to button connector. :)