Dead 2000

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@amiman99  Guess I'll have to find some DRAM chips and give it a whirl.

@JuMa  Tried that several times.  No joy.

@scuzzb494  Repeated power cycling doesn't do anything.  Double checked the INdivision and no joy there.  Firmly seated.

Looks like amiman99 has the right idea.  Now to order the chips!

Sigh...

I wouldn't put my money on chip RAM problems (the system should be alive enough in that case to produce a green screen instead of a black one) but a quick test without any extra chips is:
desolder RP502 and replace with equivalent individual resistors, such that Agnus RAS0 gets routed to U505-U508 and RAS1 gets routed nowhere (i.e. the U501-U504 bank, where a chip problem would most likely be anyway, is cut off). See the schematics for further clarification.

That way, you relocate the base chip RAM to the (most likely) good U505-U508 RAM bank. If it works, you know there's a bad chip somewhere in U501-U504.

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Don't where you got green screen.

From the standard error-colours the Amiga uses - when something's wrong with chip RAM in general (RAM chips, Agnus or possibly other custom chip, data path to chip RAM) it presents a green screen, not a black one.

Thankfully ROM is not behind the chip RAM buffers, so a problem in the chip RAM subsystem does not affect ROM code execution. Therefore if the problem is chip RAM restricted, the ROM code will still execute, detect the problem and switch to green error colour. It wouldn't normally stay black.

My startup screen is BLACK.  Just like nothing is firing.  Not even the Indivision splash screen.

Yes, you were perfectly clear about that. Which is why I suspect it's not the RAM chips (see reasoning in previous post and further explanation in this one).
The Indivision doesn't display its splash screen from chip RAM anyway, but from its internal buffer, so its absence is not an indicator of chip RAM fault.

And replacement RAM chips are on the way.

Let's hope then I'm wrong and the new chips will sort the problem out :-)