This is mainly happen if you drop your phn pretty hard or some how water went under(water vapour or humidity can cause as well). I've faced the same isuue. In my case it was for water. The lines started to come up and the display started to split. The best solution is to open up your display screen, remove cable, clean the socket and attach the cable back. After attaching use some hair dryer in a less humid place and point it directly to your phone (at midium temp)... Its fixed!