My Canon pc-d320 show install toner cartridge even after buying 2 new toner cartridges

My Canon printer pc-d320 is just showing "install new cartridge" even after I bought new toner cartridges. Where I live, most of the printer experts are try and error technicians. One said it is the cartridge sensor. I have already spent much getting two new cartridges as they advised but still no hope. I don't want to go on wasting more money. Can you please help me know what could most likely be the possible cause? And can you please give me a guide, written or video on how to fix it? I am a hardware technician so, I have no problem diserting it. I will really be grateful if you can help me out. Thank you.