Check the error displayed on the control panel and follow the instructions to remove the jammed staples. The LCD screen displays an animation that shows you how to remove jammed staples. Next, select OK to clear the error.
Do not remove the cartridge except to clear a staple jam or to replace it with a new one.
Do not open the part 
shown below if not instructed to do so.
Do not remove the cartridge when staples remain in the cartridge. You need to replace it with a new cartridge as a staple jam is likely to occur even if you reinstall it.
You need to test staple twice or so after clearing a staple jam.