Canon Imageprograf 780 " replace printhead" message

[copiertec]

I drove out to the client yesterday, 214 mile round trip. When I went out there, the PFI-107 Matte Black Ink was empty, the client failed to mention that, so I was unable to do anything because the ink is totally empty. So, we are going to ship it out to them so we can get to the next step. The client mentioned that they have been running the machine with the low ink and would turn it off then on to get it to print. So, I'm wondering if that would cause air in the printhead causing the printhead replacement error.
Customers really amaze me! I was a little pissed as I drove all the way out there and they failed to tell the front desk they were low or out of ink! I explained you can't jump to B without A first. So, once they install the Matte Black ink, they will call us if the printhead replacement message comes back up.

[Canuck]

Make sure that the firmware is upgraded...MANDATORY on all Canon wide format printers. Old firmware will cause boards to fry(main,carriage,etc) when the head gets too old and shorts.

[copiertec]

Thank you, Canuck, the firmware is up to date. As I have mentioned, I drove out to the site and the matte black was empty, customer just repalced black ink. I installed the matte black ink and have not heard back since. The problem is that the matte black ink was out and the customer just kept on turning off the machine and restarting it because, they said when the they turned it off and on, it would print a page or 2 then error out. I think the head was getting overheated possibly and causing this error. So, no call back yet for the printhead.
I explained to the client in a straight forward manner and told them not to be a bunch of idiots and replace the ink if it needs to be replaced, open your eyes and read whats on the display, out of ink means replace it. Bunch of over educated engineers that talk about quantum physics and string theory but can't read English.