This lcd has light on the screen and no OSD.The input,channel or volume on the tv or remote doesn't show up on the screen.Also the menu doesn't show on screen.
There is no way to tell if there is pic or sound,you don't know what input its on.It seems to have no effect when you push anything on remote or manually on tv.
Check power supply voltages especially 5 Volt line to micro and memory chip. otherwise could be faulty processor board or faulty micro which i think is also the character generator but I have no service manual so not 100% sure.