Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
The first thing to try, when urging a CD drive to open its tray, is to look for a pinhole near or just below or (rarely) just above the tray. Straighten the end of a paperclip, insert it into that hold and push the switch that is under that pinhole, and the tray should unlock and eject a bit, enough to pull it out the rest of the way.
If your CD drive has no pinhole, then there is still a way to trigger the unlocking and the extension of the tray (even without power). You would have to get the cover off of the drive in question, though... and if you can see the outer cover of the CD drive unit, then you should be able to see the maker label on it, identify what drive it is, and I should be able to tell you where to trigger its unlocking mechanism.
Let me know how it goes, and/or what you have to deal with, and I will advise you further as appropriate.
Well, then, to be honest, I haven't opened up a laser disc player, so I'm sure I have no specifics on this matter.
Normally I would suppose, you would work the rack-and-pinion with a small screwdriver, to urge the door open.
But, if there's a locking mechanism, it obviously has to unlock, electronically, too. (Wouldn't be much of a design otherwise!) To unlock electronically, there would have to be either an actuator, a solenoid, or perhaps a motor. Look for one of those, and the lock should be near it (excepting the motor that drives the door open - unless it has a latch-and-actuator mounted on it, maybe.)
But I cannot find a Pioneer-laser-disc-player Expert myself. I don't have that power, nor do I know of one.
I have done what I could, by Opting Out, opening this case to other Experts in this category.
ATTN: PIONEER LASER-DISC PLAYER EXPERTS, please. Thanks.