From my understanding, if you do this, the printhead can fry the main board because as it heats up, due to the clogged nozzles not firing, it somehow causes higher currents at the main board. But of course I have no direct knowledge or experience.
Did you not have to go through a refilling procedure though? I can't imagine you will get even 1/4 of extra life out of the printhead, so why bother wasting all the ink to reprime if you will just have to do it again in a few months anyway?
I would love to see the Nozzle Checks from the Service Mode to see how the nozzles degrade over time, and what it looks like when the printer says it needs to be replaced. I theorize that this could be a good way to track the health of the print head, but on my 6400 I haven't had to replace the heads yet, and on my old 6100, I never knew about the service mode nozzle check when I did have to replace them. I imagine that once too many nozzles start to get clogged in the same area, and they can't be cleared, then this is when the message comes up that you need a new head, but as I say, I'm not sure what this blocked pattern will look like or how bad it has to be before it won't print anymore.
The reason is that the nozzles are thermo-electric, and vaporize the ink droplets for ejection - ergo "bubble jet". Heads fail by the nozzles shorting out over time, and the more shorted, the more current drawn through the head.
But Canon designs a huge surplus of nozzles in the heads and auto-remaps to new nozzles replacing the old as they fail - unlike Epson, whose "cold" electro-mechanical piezo nozzles are all used. The rub with Canon is that when the spare nozzles are exhausted, the shorted-out continue to try to fire, increasing current draw and head temp, eventually to the detriment of the controller board.
So best to simply replace if a couple of cleanings don't clear the error message. More, as I was told by a Canon tech, simply a waste of ink.
With my original iPF5000 and a head failure after five years, I found it much more economical to simply replace the printer with a 5100 at $1500 - particularly as it was offered then for the same price with a $900 set of full 130ml inks. The retail value of the new printer's "expendables" was $900 for its two heads, and $600 for the started 90ml inks - the printer's cost! So facing a head failure after four more years with the 5100, with the certainty of the second head failing, I did the same (but without the bonus of the free full carts), harvested the roll spindle and cassette, for a very handy three each before the trip to the electronic re-cycle-er.
In the 10 years of lPF5000-5100 ownership - absent the rare error message - I've never done anything but an initial nozzle check on installation, going as long as 2 months without printing at times, with the same excellent IQ. I do run its calibration routine about every six months.
