Setup cartridges for printhead

[Dubudubu]

I inherited this printer and want to use it for printing posters for our charity network. Message kept saying one of cartridges was damaged or missing. New cartridges didn’t clear messsage. Thinking I was clever I removed, thoroughly cleaned and refitted printhead, all cartridges recognised but when I asked for print it gave a message about printer or ink error. 
By removing the printhead and refitting it I can go round in circles with recognition etc but cannot get it to print. 
Reading internet it would seem that I need setup cartridges - but I cannot purchase these anywhere. Can you help.

(we cannot as a local charity afford to buy a new printhead. I can provide link to our charity for anyone wishing to help. Thanks .

(I flagged message myself by mistake - oops)

regards

Dubudubu

[Repairatrooper]

HP Tech support might be able to provide a code to bypass the message and allow setup with standard cartridges. The main reason that new cartridges are demanded during setup is to ensure that no air gets into the printhead during setup due to exhausted ink.

[D Hook]

Repairatrooper is correct on the ink supply.

Just fixed a T770 that refused to complete the printhead installation.  Did some research and learned that the printer will not finish the printhead install unless the ink cartridges have plenty of ink in them.  I don't know exactly how much ink that is but I put in some used cartridges that were about 1/4 full  and then had no problem with going through the printhead install process.  Different printer and not certain it will apply to yours but it might be something to consider if any of your cartridges are low right now.