Neal ManBear
That worked well. Tried several shutdowns and restarts. No errors
Mark this as [Solved] please.

For the record
libpng error: read error - kept repeating itself
I understood that.

That is why I said, "This is the normal situation of the libpng read error." in my description of the libpng error.
tried: ctrl alt del
response: INIT: sending process to the TERM signal
response: could not log bootup address already in use
response: libpng error - keeps repeating.
tried F6 at shutdown
response: same png error sequence
ctrl alt del
response: restarting system successful.
It seems like you had some corruption in plymouth that was causing it to not complete its run.
Quite the experience. All is well. System is somewhat slower at boot, but no hard reset linux heart attacks. Have no clue what a "plymouth" is or does.
I truly appreciate the support.
Thank You all.
Plymouth runs the sequence of boot graphics.