Try to let it ON for a while. It works for my Pioneer DV-626D!
But my DVD player is going down again regularly. Still turning it on and waiting for a while (10-15 minutes but just turn it on and forget about it) always works.
While waiting you may want to unplug it from the TV set, particularly if you are using a SCART plug ("prise PERITEL" in France) as the DVD player is going ON and OFF for a while hence switching each time the TV to the external channel.
Raoul