'''++hokshy++''' sounds like your screen damage is causing this. It may have worked somewhat in the beginning but the damage is extending. It is probably shortening out and causing the rest of your tablet to heat up. It is illuminated since the backlight (separate circuitry) still comes on. You cannot properly diagnose this until you replace the screen. Use something like [https://www.youtube.com/watch?v=eJAQfsmH17M|this video] to work on it. Since there are no guides for this repair on iFixit I would also suggest that you create one for the rest of us. https://www.ifixit.com/Guide/new