If you have bought refilled or remanufactured Canon PG540 CL541 ink cartridges your printer will always read your cartridges as used or partly used.  This is because the chip on the cartridge cannot be reset even after refilling.

A pop up may appear immediately or shortly after installation or whilst printing stating the cartridges are empty and you need to follow the following instructions before you can resume printing.

• Press and hold the printer 'STOP' button for a minimum of 5 seconds.  The stop button looks like a circle with an inverted triangle inside.  Once the cartridges have been reset you normally hear the printer make a noise and you can release your finger. You may need to do this again at some point in the future if you have installed two ink cartridges but you will only need to do this once per cartridge.