HP 6700 Premium error message: Ink System Failure and Missing or failed printhead

[TechBuff7]

My HP6700 Premium was working fine until the landlord shut off the power in my room from the electrical panel in the basement to fix an outlet in another room. When my power was turned back on, my printer displayed the following message, " There is a problem with the printer or ink system. Turn printer off, then on. If problem persists, contact HP." When I hit the OK button on the display, the following message then appears, "The printhead appears to be missing, not detected, or incorrectly installed."
 
The error messages do not allow me to use the touch panel and I cannot print from anywhere. The printhead is fixed on this model. I cleaned the contacts on the ink cartridges and that did not work. I also tried resetting the printer by unplugging the cord from the printer and from the power outlet, and turning it back on multiple times and that did not work. I tried to factory reset the printer doing the same steps with the cord and holding the power button on for a few seconds, seeing the light blink to indicate the reset. That did not work. I even plugged the printer in different outlets and I received the same error messages. I checked my firmware and it is up to date. The ink cartridges are not depleted according to the HP Smart app, the HP Utility on my Mac and the embedded web server. I could use the scan function by using the HP easy scan software on my Mac but I cannot print from anywhere and I cannot access the touch screen panel due to the error messages. The messages appear to be in a loop on the display. What else can I do?

[8lives]

You have done all the steps that HP recommends , printer will have to be replaced.