Press 'OPEN / CLOSE' on the front panel, so that you operate when the tray is open.
Use the Remote Control unit to slowly key in 9 , 9 , 9 , 9, 0 in that order.
Press 'OPEN / CLOSE' again, the DVD player will return to normal operation.
Sometimes it is required to set specific region. You can achieve that on Philips DVD player by put 9 9 9 9 X where X is the required region number