Mac Pro Tower 2019 Will Not Boot

Thank you Varjak for the quick response. I suppose I may have introduced static but in our area, the humidity runs about 70% so we normally don't have this issue. That said, anything is possible - perhaps there was static in the line???. I imagine that is a possibility. I did previously go through everything listed in the link that you attached...even went as far as replacing the memory (I just upgraded the memory a few weeks ago). Maybe I'm doing something wrong.

After doing a bit of research on Pram batteries, I came upon someone else's suggestion as follows:

Remove AC power cord.

Press the power-on button for a quarter minute. This completely depletes the power capacitors, taking all Voltages inside to Zero except the PRAM backup battery.

restore AC power cord

wait a quarter minute.

Power on as usual.

After following these instructions, the computer powered up and came to life! I did get a Panic Medic Boot message that stated "A third party kernel extension was preventing the machine from successfully booting." I have no idea what that means.

Of course...another issue. When the machine did power back on and seemed ok, I turned it off, replaced the old memory with the relatively new memory and I got a flashing amber light when I attempted to power on the machine. I then put the old memory back in, and the machine powered right up. Adding to the mystery, I am now getting software conflict notifications...Printer software/Wacom Tablet software not compatible. I wasn't having any trouble with this before.

Honestly, when I replaced the memory a few weeks ago, it did not seem that complicated (and yes, I did read and follow all the instructions). I had 6 original DIMMs (8 GB each) and they were replaced with 6 DIMMs (32 GB each) in the same slots - no struggle. The new memory was working fine.

Not sure I understand what "Drop main power" means...but I did power down the Mac before adding the extension.

Gotcha. No. I did not remove the power cord when I added the extension.