I am not sure what you need help with tonight. Is it that you have already replaced one of the 4 toner cartridges and it keeps asking to replace it, or that you don't know how to open the left side of the printer to replace that toner cartridge? If it's the former, the crum chip on the toner cartridge may be defective and is not being seen by the printer. That can usually be confirmed by another cartridge being installed and returning the one if it's still under warranty as a defective cartridge.
Answers & Comments
I am not sure what you need help with tonight. Is it that you have already replaced one of the 4 toner cartridges and it keeps asking to replace it, or that you don't know how to open the left side of the printer to replace that toner cartridge?
If it's the former, the crum chip on the toner cartridge may be defective and is not being seen by the printer. That can usually be confirmed by another cartridge being installed and returning the one if it's still under warranty as a defective cartridge.