Need to factory reset HP Officejet Pro 8600 Plus - other posts don't work

[MikeDempsey]

After following the recommended cleaning procedure for the print head [after having stupidly removed the ink tanks weeks ago] and re-installing the new cartridges (I had installed them briefly before I realized it needed cleaning to remove clogs) it still tells me all 4 cartridges are bad.

After the cleaning it showed 4 nice/complete colored lines when I lightly press the print head onto a damp tissue which seems to show that ink is flowing fine through the head.

I read somewhere that these printers 'remember' the previous set of empty/bad cartridges so that you can't simply refill and re-use them and I suspect that's the problem. (Maybe they remember more than 1, who knows.)

I found a couple of posts that both pointed to a web page that contained instructions to do a factory reset using a 'hidden' menu that can be accessed during startup. However the article told me to press the 'Back' button 4 times during startup ... but the back button is not displayed during startup. (and pressing where it 'should' be displayed does nothing.)

[banhien]

@MikeDempsey 

Please try

  https://h30434.www3.hp.com/t5/Printers-Archive-Read-Only/How-to-reset-Officejet-Pro-8600-Plus-Premiu...

or

   http://resetprinters.com/how-to-reset-the-hp-officejet-pro-8600-premium-all-in-one-printer/

Regards.

[MikeDempsey]

Those are the 2 links I had previously read but the Back button does not show up when I start the printer, and pressing where the button 'would' be displayed does nothing either. (That was the second solution given)