Hi, I am trying to solve the dreaded "WRONG CARTRIDGE" error, which according to various forums would be a consequence of a clogged printhead.
However, there is something else strange with this, even after removing all of the cartridges and turning off the power and waiting for 7 minutes, after plugging in the cable again, it shows all cartridges as in there with ink levels totally filled.
So where is this actually detected, probably some sensor is covered which makes it think the cartridges are still there and filled completely.
Based on your description of the issue, it would appear that your PIXMA MP780 would require service. If your PIXMA MP780 was purchased less than a year ago, please contact one of Canon's Technical Support Representatives via phone or chat to obtain your in warranty options. To contact a Technical Support Representative, please use the link below:
If your PIXMA MP780 is out of warranty, you are eligible for Canon's Upgrade Program. This is for out of warranty units which have been diagnosed to require service, or for some reason are incompatible with a new or upgraded system. This option allows you a one-time opportunity to purchase a replacement product, discounted from the list price.
If you would like to take part in this option, please call our Sales Department at (866) 443-8002 Monday through Saturday, 9am to 9pm. Let them know you have been working with technical support and the Canon Upgrade Program was offered.