Can't remove cd cartridge because won't power up.

With the top off the unit, you can turn the tray gears manually for slow eject function. Unplug unit before touching anything inside, check internal fuses.
Sometimes the little ball bearings that keep the cart trays separated come out causing tray jams and shorts.
Make sure your tray retracts all the way into the player flush with the face plate when loading, gently push it in while retracting for those occasional no-read situations. (Also for Denon that takes these same carts). Also note that the CDs go in the Upside Down position.
Applicable to:
Lexus Models: CDX-M9071zt CDX-M8036, CDX-M9071, CDX-M9741, CDX-M9751
also:
Philips CDC-875 Pioneer CDX-FM35 Pioneer CDX-FM45 Pioneer CDX-M30 Pioneer CDX-M40 Pioneer PD-DM802

* Pioneer PD-DM902 Pioneer PD-M403 Pioneer PD-M423 Pioneer PD-M426 Pioneer PD-M450 PD-M453 PD-M455
* Pioneer PD-M501 Pioneer PD-M502 PD-M503 Pioneer PD-M510 Pioneer PD-M530 Pioneer PD-M550 Pioneer PD-M552 Pioneer
* PD-M600 PD-M601 PD-M603 Pioneer PD-M610 Pioneer PD-M630 Pioneer PD-M650
* Pioneer PD-M701 Pioneer PD-M702 Pioneer PD-M703 Pioneer PD-M710 Pioneer PD-M730
* Pioneer PD-M801 Pioneer PD-TM1 Pioneer PD-TM2 Pioneer PD-TM3 Pioneer CCS-430
* DCM-444 and DCM 777
Many Magnavox, Denon, JVC,
BMW 740 OEM and others.