Hello fellow techies Beware folks, turns out pioneer is booby trapping their products these days. You get the top cover off, you see a "case open switch" which opens once the top's off. If you now power up the set, with the switch open, your unit gets "locked". Both standby and power on l.e.d.s glow together and this state is listed in the service manual as "trap switch operation" under the LED-lighting patterns/error codes section. A little googling led me to this post.....
The service manual explains it so...... For video data transmission from the Media Receiver to the PDP-434HD and PDP-504HD-series Plasma Displays, digital signals are used. Therefore, this unit adopts the HDCP (High-bandwidth Digital Content Protection) system for copyright protection. This unit is also provided with a detection switch (TRAP switch) that will prohibit the unit from being turned on again "if the upper plate of the unit is accidentally opened," in order to prevent the panel technology from being leaked out. The TRAP switch is disabled while the unit is turned off. When performing internal diagnosis of the PDP, fix the switch to the OFF position using adhesive tape before turning on the unit. After servicing, be sure to remove the adhesive tape.
Well you've probably guessed what my next question is......How do i unlock this receiver????????? Thanx in advance, Jango