I have a lg dp181.

the problem could be the display or it could be on the internal board.

if its the display and I suspect it is since when you adjust the brightness it goes off. It could be a bad inventer on the display, do you still have a faint picture on the screen? that would indicate that only the backlight goes off and the issue is only the backlight / inventer.

if the issue is on the board it might not be repairable without replacing the whole board, and at that point the price might come close to a new one.

finding parts for these players also might be difficult.

have a look at the display under a flashlight or any other light, or does the unit turn off completely?