Sure, okay, sorry. On instructions from tsialex, who has been wonderfully patient and helpful, via email, I got a new flash drive (the one I'd been working with was bad), and turned it into an El Capitan boot drive. One of his instructions included: "Do a BootROM dump using ROMTool, attached here. You need SIP disabled and no AV/anti-malware running. ROMTool is usually a false-positive to every AV/anti-malware because flashrom and DirectHWAcess.kext." So I disabled SIP, tried to run the RomTool, it asked for a password which I assumed I didn't have after trying the administrator password, and thought running the 2009-2010 firmware update, since I'd finally been able to disable SIP, would work.
This is exactly what tsialex was trying to prevent. He wanted me to send him the results of the BootRom dump so he could help me. So, after running the firmware update, shutting down the Mac Pro and starting it by pressing the power button until it flashed and beeped, my display showed a different apple-and-status bar than I'd seen before (thicker, and sort of white with darker edges), and then turned off.
I expected, finally, to start it and be able to see the 5,1 in the "about this Mac" screen, but it just wouldn't boot as the ROM chip on the backplane no longer works due to my ineptitude. Doesn't matter if I have the hard drives out and try to boot from the flash drive, the ROM chip in the backplane has the wrong information on it and that's a hardware issue--as I understand it. After explaining what happened, and asking for clarity, as I know very little, he wrote:
"The backplane can boot from an external SPI flash connected to the LITTLE FRANK connector.
ROMTool zip package password is just to decompress the package, don't flash anything. ROMTool process at this time is just to read the BootROM. You probably did something before, like Netkas procedure [Yup].
SMC is the System Management Controller. 2009 CPU trays and backplanes have SMC 1.139f5 version, 2010/2012 boards have 1.39f11, you can't mix 2009 with 2010/2012 boards. SMC with different versions don't work and the fans go full RPM.
You should create a thread asking if someone local to you can help you repair your board.".
Instead of creating that thread, I decided to post on this one.
Is that the detail you were looking for? I'm guessing I need either an external SPI flash, another backplane, or another 2009 4,1 ROM chip and find someone that can desolder the ROM chip I hosed, and solder the new one on? Again, sorry, I'm justifiably annoying at how little I understand, so I imagine if I haven't yet offered enough/the right kind of detail, I'm not easy to help.
Thanks,
--Gil
P.S.: I want to again mention how patient and helpful tsialex has been with me. He continued to email me instructions and offer help well after the "this guy is annoyingly ignorant/unprepared" point.
