my ipad mini 2 has a screen glitch whereby there is a green strip and white strip obstructing half of the screen. any ideas?

iv had my ipad mini 2 for about a year. without any interference (a knock or contact with water) it developed a green strip all down the screen, about an inch thick. there is white strips on either side, all obstructing a view of about half of the screen, although it is still otherwise fully functioning.