LG RH177 record and play problem

I have a dvdrecorder LGRH177. When I want to record, I press REC button and after a few minutes it stop automatically stops, like I press STOP button.Same problem and playback. I changed the bios SL32 to SL40, I changed the firmaware, but I don`t fix the problem. And when I turned off now must to press twice to turn off. I press first the button, on display write turned off and then a press once again and the dvd is turned off.