Hi your problem is:
Power cycle the printer.
Then Reset the Printer.
If still exist, problem is the scanner assembly.
Here are the tip on how to Power Cycle:
Verify that the unit is switched on. Unplug the all-in-one from power and disconnect the connection port.
Wait 30 seconds.
Plug in the power only.
Repeat steps 1-3 two more times.
On the third time after plugging the unit into power, reconnect the connection port from the all-in-one to your computer.
Partial reset is one kind of partially reset the printer.
If i am helpful please rate me.