Casio SE-C3500 User Manual page 7

To use the cash register's basic function
„ When the cash drawer does not open!
In case of power failure or the machine is in malfunction,
the cash drawer does not open automatically. Even in
these cases, you can open the cash drawer by pulling
Drawer release lever
drawer release lever (see below).
Important: The drawer will not open, if it is locked with a
drawer lock key.
E-7