Error message "rear door open" on the printer.
Do a power reset to see if that solves problem.
With printer turned on, disconnect the power cable from the rear printer.
Now disconnect the power cable from the wall outlet.
Wait a minute and reconnect the power cable. Restore power. Is error message gone?
Be sure to use wall outlet. Don't use a power hub or a surge protector.
If you Flip the back door down, you will see two plastic pieces near top.
Are they perhaps broken off. With door closed, tab on the left side goes into a hole to activate door sensor to indicate the door is closed. Sensor switch could also be defective. Replace switch if plastic pieces intact (not broken).
Advise