I had the same issue after my macbook fell from the table: flickering pixels and sometimes flashes. I fixed it easily, maybe this will be helpful for somebody: (1) Open the backplate (2) Check for the loose connectors (3) Gently push in connectors with a plastic tool. (4) In my case some connector just got loose after the hit. I guess it was the main display cable connector near the charging port (5) Wish you all luck :)