Issue apparently resolved itself on a third go. Now able to log-in via http://localhost:3000, the admin panel indicates v0.29.2, and everything appears to have migrated and is functional… No clue as to what could have possibly caused the loop issue… My apologies for having taken up everyone’s valuable time, thank you for your patience and input!
Spoke too soon, issue remains. Uninstalled Composer (installed few hours prior to all this) and trying again. If issue persists will open up a GitHub ticket.
Gave up, unable to re-establish even with the old jar file… Submitted GitHub ticket #7628
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ISSUE RESOLVED!
Double clicking the jar file THEN immediately launching from the command prompt w/ java -jar metabase.jar — That solves the problem! — This also applies w/ java -jar metabase.jar migrate release-locks.
Took a chance that it would do the trick because normally when downloading software in the form of exe files one simply double clicks to launch the installation process.
Nowhere in the Running the Metabase Jar File or elsewhere (that I can find) is this minor detail mentioned.