able to bar over the engine
 

I was able to bar over the engine, with minimal resistance.

test at the starter relay and ignition switch and see if they are putting out volts to the starter when key is turned to start

I’ve tried to upload a vid of the “thunk” sound when trying to start the car, but unable.

You can hear the fuel pumping when I turn the key to Run, then the thunk when turned to crank, which sounds like the Solenoid is engaging the bendix(?), but the starter doesn’t turn, then about 10 seconds after the last crank of key, there’s a sproing sound, like the return of the bendix to the original position?

Thanks craby,
But since the Solenoid is engaging (just updated above), would that nullify the ignition switch test? I'll do it if needed, but accessing the ignition switch may be more painful (nerve damage in neck) than I can bear, prefer to avoid until necessary.
I'm wondering if my "new" duralast starter has a bad connection Solenoid-to-starter, or maybe a bad ground...somewhere?
I've been trying to find how to verify a bad starter motor ground, but all the vids seem focused on the Solenoid itself.
I'll get back under her tomorrow, today is IMSA Sebring day.
First test, checking continuity from solenoid to starter connection.
Then, check for ground locations.

Is there a specific ground location for the starter?
2000 v6 3800 series II, vin K, 3.8L, coupe.

Found a Power Distribution diagram:
G102- Left Front shock tower (this is the one that allowed the crank)
G119- Right Front of engine (for 3.8L).
G120- Right side of engine block
G125- Front of engine
That's what I've found so far to inspect.

Found where to look for solenoid starter ground location from the service manual, pg.3657

if you have long jumper cables try jumping the battery ground to the starter base and see what happens.

the starter is grounded through the engine block. I ran an extra ground wire to my block from the battery just for piece of mind looking for reason my voltage was low at the gage, I finally gave up and let it read low. runs fine just didnt like the lower volt reading at the fuse box.

Craby, thanx, will do.

well, that didn't last long ANOTHER NEW STARTER, STILL NO JOY
 

I returned the starter, I thought it had a bad re-man'd connection from solenoid to starter motor. Now on my 3rd starter( the first one was cracked at one of the mounting bolt holes, and wasn't the right one for my car(insert head banging) I had it bench tested at the store before leaving with it,and still have rhe same problem, click-no start. I don't have the right test leads for a voltage drop test, the alligator leads I bought from HF wont register continuity, neither HD nor Lowes have any in stock and shipping won't happen til May9, so that's on hold for now. I'm wondering if its possible I got another bad starter? And I should just order an Ac Delco from RockAuto instead of this reman ****. I'm at a loss here, since I still have the original problem, even with 2 new (autozone reman) starters.
Craby, I tried your jumper cable to the starter housing, no joy there either .driving me nuts! I followed the harness from battery (+) to the solenoid and the ground strap sol-to-ground strap continuity checked ok, solenoid still engages with key turn, just won't crank.
Security light does blink and turn off, now have "service engine soon"light stays on.
Hooked up Autel MaxiAP200 OBDII scan, no history of codes, will admit that I have no idea what I'm doing though.
Plan: Hooked up battery charger, was reading 12.3 on DMM, thinking of hooking up jumper cable from battery (+) to solenoid B-post and seeing if that does anything, unless someone says that would be a bad idea. Much help needed, thanx

Also...
 

Solenoid only engages in PARK and NEUTRAL, ruling out PNSS.
Migraine protesting too much to get under car today