The rear door on my 2003 Rx300 will not open using either the interior or exterior handle. The door lock actuator appears to be operating normally. I do not recall exactly how it came about. I would appreciate any insight on how to resolve the issue. I anticipate that I will need to remove the door panel which will be difficult with the door in the closed position.

 

Hmmm. Can't check child lock until you get the door open. Some cars create access by removing arm rest and possibly the trim around the interior latch/handle. If so maybe you can see or access an ability to operate latch. I'd also take a good look at removing the panel with a proper tool. You said you anticipated this to be an issue on a closed door. Look to confirm instead of speculating. I bet you CAN get the panel off. BTW, I found over a dozen youtube videos on this subject. Best wishes.