Take it apart and inspect the display connectors and cables for damage. By the looks of it you did leave a few fingerprints on the LCD but that’s not a huge issue as you can gently wipe them off. Anyways if the connectors look good I would try another LCD. If a new LCD still shows the same problem them you’ve probably got a board issue on your hands and it will need to be repaired by a microsoldering specialist. Did you make sure to disconnect the battery and put something under the board between the battery before disconnecting the screen?