Printing Errors or Lights & Stuck Print Jobs

I get the message "Printer Failure There is a problem with the printer or ink system" (no error code). It had been working for a year or so, suddenly this message appeared.  We didn't move it, we did not connect to a new network or do anthing to it's wifi or connectivity.  And we did not replace cartridges.  It just did this all by itself, suddenly.   On startup, i get the normal control panel for less than 2 seconds then this message appears.  I CANNOT get back to the control panel to do anything, because all I get is this message.  If I click on the ? next to the screen, it tells me to (1)unplug and restart the printer.  (2) contact HP support.  So I cannot see any displays, and I cannot print a test message from the printer, and I cannot update the firmware, because I'm locked out.

1.When I turn it off, unplug, replug, the printhead moves fine, I hear it as normal.  But all the while the error message is displayed.  If I unplug it without turning it off, and plug back in, the same.

2. I tried HP Scan and Print Doctor, and it can see the printer, but says "your printer seems to have a serious issue.  I cannot print either an external or internal test page.

3. I removed each cartridge, and they all look fine, no leaking.

4. I removed the printhead, it looked fine (there was a LOT of black ink on the contacts, but the black cartridge did not appear to be leaking when I examined it).  I replaced the printhead, and it did the same.  I then reseated the print head twice more, and it did not help.

Steve