OK, I can help, but I wonder how you got into this error? What we need to do is called an "Initial Reset"
Insert the "P" key and turn to "P" for Program. Now press the Subtotal key and hold it down while you switch the register off by the switch on the right side above the cash drawer. While still holding the subtotal key down, turn the switch on the right back on continuing to hold the subtotal down until the register prints "Initial Reset".
Now when you turn the key back to Reg, the display will say "Closed". Sign on a clerk by pressing a 1 and the "clerk key", located on the top right of the keyboard.
This should get you going but write it down so next time you will know.
Let me know that this worked.....
If you know exactly how you got into this E20, please let me know, thanks