Epson LQ-500 - Page 104

The Interface Boards
4. Insert a flat-blade screwdriver into either opening on the
underside of the printer. Push the screwdriver up and press the
handle of the driver toward the back of the printer to release
the clips on the case.
5.
Partially raise the upper case, taking care not to strain the flat
cable attached to the control panel.
Appendix A-5