Sony PCV-RS400 - Manual (Page 27)

About the Remote Control
27
To set up the remote control
Insert two AA batteries (supplied) into the remote control as shown.
Inserting batteries into the remote control
✍
If your remote control does not operate properly, the batteries may need to be
replaced. When your remote control is not being used for extended periods of time,
remove the batteries to avoid possible damage from battery leakage.