I'm going to try and recount the EXACT steps I tried and the outcome of each.
So the lesson here is just remove all of the damn cables from the back of the AVR, even if you think you know better.
- I get home from the airport, get everyone settled and go change my clothes.
- I immediately turn the receiver on, and the list of NG error codes has grown. Before I had 2R2L (or the reverse..my brain hurts) and that was it. Now, the whole list takes a while to jump through. Yikes.
- I tried to factory reset with the CBL + STANDBY method. Nothing. It won't respond at all to anything but turning it off and on. I had bookmarked a post that mentioned sometimes the factory reset procedure won't work and you have to use an alternate procedure. It involves holding down the ENTER button instead of CBL.
- ENTER + STANDBY (I hope I have this combination correct, please correct me if I don't) works, BUT it goes straight into Amp DIag mode on the display. Up until this point, the words "Amp Diag" was *NOT* appearing on the display, just the error codes.
- AMG DIAG mode tells me to "CH SPWIRE" or whatever slang it's using to tell me to check the speaker wire.
- I tried just removing the suspect wires (from the trash can contact) and receiver still tells me to check the wire.
- At this point, I am done trying to ignore the advice that I've read before....."Unplug EVERYTHING from the back", and I unplug JUST the channels that are powered by the receiver. I figured the channels that are pre out to an external amplifier would be less likely to be a culprit. This doesn't work.
- I then unplug about 4 or 5 of the externally amplified channels and turn it back on.
- SUCCESS!!! I run the initial setup and verify I can hear audio from the correct speakers.
- I connect the remaining channels one at a time and verify correct sound. After doing 2 channels this way I reconnected everything back to the RZ50 just like it was before it imploded. Everything is still working. No diag mode.
- I fired up Godzilla Minus One and proceeded to shake the house off of its foundation. No diag mode.
So the lesson here is just remove all of the damn cables from the back of the AVR, even if you think you know better.