My printer is also just over a year old and I started getting the same error last night and it will not go away. There is NO paper anywhere that is visible. The levers are pushed back down. Apparently I have a giant, useless paperweight now.
I have removed the four screws that are on the back and the back cover will not come off. It appears to be attached to the sides somehow and I can't get that off without breaking something or completely disassembling the printer.