The Problem is finally solved.
I removed the Oil Pan.
Next, I cleaned it real good with the power washer, so I could handle it in the garage to work on loosening the plug.
I chipped the JB Weld away with a chisel and hammer. That part took about 5 minutes.
Next, I drilled a hole right through the plug. This was definitely not a hollow plug. It took me about 30 minutes. Finally was able to remove the plug by putting the 1/4" Screw extractor on the inner side of the plug and using power drill in reverse to get it to come out.
I washed off the shavings and debris from the inside of the pan and inserted new drain plug. It was very snug at first but fit in quite nicely. There was little doubt this time when the plug was in tight enough. I poured water in the pan to make sure it wouldn't leak. It was rock solid.
I cleaned it once again and thoroughly dried it. Next, I went to the auto parts store.
Gasket appeared to be in good shape. At the recommendation of the auto parts store, I used some RTV Black Gasket Maker over the top of the current, intact gasket.
Re-assembled..Put in brand new, crystal clean oil. This has gotta be the cleanest the engine oil has been since it was new, being that this is the second time I've changed the oil in 7 days.
I Ran engine for a while. No leaks. Plug appeared to be bone dry. It will be a few weeks before I know for sure it the gasket seal is lock tight.
One small mistake. Doing this in the dark, I slightly overfilled the oil.. It's about 1/10th of a quart high. That could settle after a while as I was check this pretty soon after filling and running engine a few minutes.
Hopefully, 1/10th of quart high isn't a huge risk? I don't have the heart to loosen the plug again!
One Note: While it is rather easy to remove the oil pan from the 540i, it is secured by about 20 bolts..Very time consuming and tiring doing these by hand. Use a re-chargeable screw driver with a 10mm socket to make the process faster.
Thanks for all the help and feedback. Couldn't have done this or even tried it without your help.