I found the problem with my CH-DVD 300 red light power problem where one can't turn it on or off. It was a defective motor which spins the disk within the DVD player. The motor's carbon brushes had disintegrated into dust within the motor. I cleaned it up, soldered copper leaf brushes to the former/defective brush holder arms and now it plays.
How can you tell if you have a defective drive motor? Remove the steel DVD player's cover. With disk inserted, spin it with a finger. This will hopefully change the LED color from red to green. The player is expecting the disc to spin once inserted and if it doesn't, you get the red indicating light.
If you are good with a minimal amount of small tools I can provide further details. Let me know if there is any interest.
I wonder if the weakest component in this popular player from the 2004 era is the drive motor and specifically, its carbon brushes.