You are wrong. The OP has not tested with a System Card.
If the door switch is open, it will say "please close". If it thinks it is closed, the light will flash as it attempts to read. As it is now, the CD part simply seems unresponsive. My guess is that the OP has the same issue.
System Cards will always start, even on a first gen PC Engine with no CD ROM attachment. But they will get stuck at the "please wait" screen.
If the door switch is open, it will say "please close". If it thinks it is closed, the light will flash as it attempts to read. As it is now, the CD part simply seems unresponsive. My guess is that the OP has the same issue.
System Cards will always start, even on a first gen PC Engine with no CD ROM attachment. But they will get stuck at the "please wait" screen.


10/31/2023: Localization News - Dead of the Brain 1!