Panasonic Toughbook CF-52AJC15AM Reference Manual page 22

Battery Power
To insert
Insert the battery pack until it securely fits the connector.
4
Slide the cover back.
Push the cover until it clicks.
CAUTION
Make sure the latch is securely locked, otherwise the battery pack may fall when you carry the computer.
Do not remove the battery pack forcibly when the latch is locked. Doing so may damage the battery pack.
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