Damaged vs. Defective Cartridges and Printhead

[klbabb]

This is a summary of what I am going through – an ink issue rather than a plotter issue?

1.  Message came up that I needed to replace the black cartridge.
2. I opened an unexpired (03/24) black cartridge.  The control panel then told me that I needed to install C/Y/M cartridges.  I pulled out my spares and installed those.  Now the message came up that “One or more cartridges appear to be damaged (k) . Remove and Replace Cartridges”
3. I removed it and reinserted it a few times.  Eventually, I got a “change printerhead” message.
4. I ordered a new print head from Staples that took a week to get here.  When I went to install it, the first time I put in what were “new” full cartridges from my stash.  I then got the message that I needed to install all new cartridges with the new printhead, so I installed the startup cartridges that came with the new printhead.  The message that came up continually with the new printhead was “Not enough ink to complete startup.  Cartridges used during initialization must be NEW.  Open Ink Door to replace indicated cartridges or press IL to insert another PHA”.  New printhead, new cartridges, all with expirations of 08 or 09/2025.
5. I then put in the old printhead and the other set of older new cartridges, and it went back to the “Damaged K cartridge” message. 
6. I have ordered another K cartridge from Staples, which will probably take another week to get.  Meanwhile, I have a Designjet 711 Printhead Replacement Kit that is absolutely worthless.  My printer will not accept it, Staples will not let me return it, and I can’t get a response from the online message team.  They first contacted me late in the day on a Saturday, and then again late in the evening on Sunday – non-office hours, where I could not respond due to  not being in my office.
7. This morning, I finally had a response – asked for all of the pertinent info as well as photos of the ink cartridges.  I finally got a response after 5+ hours, I got the following response: “ I understand that you need help with your HP Designjet T520 36. Your HP Designjet T520 36 is classified as a Commercial product. We have a dedicated team who are trained on these type of Commercial products. For information on this product, please contact our Commercial Support Team by filling the web form using this link - www.hp.com/contacthp - On that page, where it says to enter my HP model number, enter your product details and click on find my product - On the next page, it will ask you to enter your basic details and the description of the issue. - Once you have filled that, click on show options. - It will give you phone support option. - Once you select that it will give you a case number and a phone number to contact. Regards, Damini- HP Social Media Support”
8. I go to that link, and it is now saying that my support is expired.  Is it expired for the useless Printhead replacement kit that I can’t return?  I have asked all “HP experts” and have not found a workable solution.  Additionally there is not an HP Authorized Service Center anywhere near me.  What to do?  Switch to Canon?  I am totally annoyed with HP.  I have had 4 HP plotters now.  What to do?  Switch to Canon?