I've got here with a different problem, but somehow the same. My MG7720 printer got the printhead squares double walls but printing all the colours somehow ok. Doing an automatic and manual cleaning made the colours better but the lines at the top of the page were still double - issue reflected in the text as well. Many rows printed with double letters.
Talking with Canon support I ended up ordering a new printhead & set of ink cartridges - which did solve the issue with the double letters but now my printer print NO Colors at all. As you can see in my Nozzle Check below, no colours are coming out. Nothing with the old printhead, nothing with the new printhead. Brand new ink cartridges, regular cleaning, deep cleaning, nothing works.
The only error I have is when I do an Automatic Printhead Alignment I get the 2500 error as is in the below screenshot. Anyone any idea what's wrong with this printer?
Canon doesn't seem to be any worried about my problems with their product even after spending so much money on new ink and new printhead. Please help!
Automatic Printhead Alignment Error with NEW Canon Printhead: