First,if you take out the card before playback.
Second,ensure that the DVDs is clean, no scratches.
Third,put the DVD flatly, otherwise it will affect the reading.
Fourth,maybe the lens gets dirty,you can wipe it lightly by using a swabs or clean cloth.
Fifth,if there is still "OPEN" on the top left corner of the screen after you close the cover,cause the triggered switch on the mainboard is off,in this situation,you must tell me which model do you have,I will send you a operation demo.
regards