I checked the output voltage of the supply and it is 19.5 volts. Using the installed HP battery checker, it shows a good battery at 100%.
New information. If I power ON from total shut down, the HP logo appears during boot. The screen goes Black. If I press the Power button the laptop goes into Sleep. I can see the Power light on the left front blinking. I am pretty sure this means it is in sleep mode. Pressing the Power button again the normal splash screen immediately appears and I can proceed to log on with normal operation.

I have pressed the power button for 15 seconds with the battery and external power removed. I reinstalled the BIOS. I also reinstalled win10 from MS. No new hardware has been installed. The OJ5740 printer driver was installed.
Since this is out of warrantee, if the problem can not be resolved I'll instruct the user on my power button procedure.

Any suggestions?
Regards,