Dvd IN lOGIC TV is not working

I have purchased a new logic 19" flat screen TV. The in built DVD player will not run dvd's. It worked originally one time. When I now switch to DVD mode the "no signal" text comes up on the screen and the DVD will not even spin. I fitted a wall mounted bracket to the back of the set after trying the tv originally when the dvd did run - could this have had any affect on the unit ?