A backup is a great thing, good note!
The Pi 4 has been running with no problems. I believe the issue was the power on the Pi 3B+. Also, I'm now sure the older printer was causing a USB power issue as well. When plugged in, it would not allow the Pi 4 to boot up. Once I disabled the USB power pin for the older printer, the Pi 4 boots fine. My problem may have been both the power supply for the Pi 3B+ and the older printer USB power pin combined.
I believe the problem has been diagnosed as a power issue and has been solved.
ThanX