Panasonic AV-HS04M3 Operating Instructions Manual page 10

Mounting
 Align the board with the guide rails, and insert it slowly.
Insert it all the way in. Take care not to use force to insert the board because the
connectors may be damaged in the process.
 Attach the board using the two screws.
 After connecting the necessary cables, plug in the power cord, and turn on the power.
Screw
9 (E)
Screw