OK - the XE90fx is definitely a Xerox device, but I assure you, 'XE909fx' brought up absolutely nothing.
Press the pink Clear button and the button below the word Auto, like this:
CLEAR - AUTO - CLEAR - AUTO
and all the lights on the control panel of the device should go out.
Then, press the [10s] key once, and the [1s] key four times over, to enter
on the LCD display.
Press the START button, and press the CLEAR button two times.
This should, if it 'goes through', clear the error. It's a reset, and may clear the E7 error.
Let me know how it goes.