If the cartridge holder is stuck, you will get the 5011 error. Canon suggests that the printer must be repaired, in some cases repair is required but before you turn your printer over to Canon; try the following steps as it may fix the issue:
1. Unplug your printer and let it stay off for 3 minutes, then power it back on and test.
If it doesn’t work, then turn it off again.
2. Lift the lid from the printer, including the scanner. With the lid open, turn the printer back on.
3. Then close the lid and see if that fixes the issue.
If it doesn’t work, then the printer needs to be returned for repair. If your printer is out of warranty, then it will be best to get a new printer as they only cost less then $60