Getting error message: Missing OPT or all print heads

[HSS25]

My Hp Latex 365 printer was working perfectly.  Problem started with missing Blue colour in the print. We checked the printhead test plot and fond two printheads CK and Opt are not working.

We purchased new printheads and replaced. First thing we did we print the printhead test plot and find our missing Blue colour but the black was not completely printed. We decided to clean all printheads and fixed them back on their location.  Once we did this step we have found new multiples errors of missing printheads on printer screen. Printer stopped recognizing all printheads. As per the test procedure if we install printhead one by one the printer detects them all except the Opt printhaed, but when the printhead carriage moved back to its location it give error again of defective printhead and when you check all the printer show missing all printheads.

We thought the new printheads could be defective so we put the old printheads back in the printer but the error messages never stop and the printer still did not recognized the old printheads, keep showing errors of missing printheads?

To our best knowledge did several times carefully cleaning of all printheads, printheads contacts strip, swapped new and old heads and switch OFF / ON power of the printer but nothing works until now.

Now we are in a new situation and we don’t know what happened and how to come out from this situation? 

Please help and advice.