Pioneer CD/Minidisc Player FH-P9000MD Pro...

The remote control missing shouldn't be a factor - Pioneers will usually select the same sources with the "source" button as they will with the remote.

I would suggest 2 things - first, try different CDs. If it's accepting and ejecting just fine it may be a problem with reading your CD (I'm assuming you haven't tried this already). Ideally use a regular audio CD (not an MP3/WMA disc) that is relatively scratch free.

If that doesn't work, check to see if the initial settings can be adjusted to enable CD play.
To get to the initial settings menu you need to hold the "source" button until the unit powers off (the car's key will still need to be on at this point). Push and hold the "function" button and it should go into a menu with various adjustments, such as clock, aux enable, etc...
There may be a setting in there to enable CD play. I realize that the display may also be in Japanese but I'm hoping it will be somewhat intuitive for you - you seem to have a decent technical grasp on things already.