Mitsubishi Electric MELSEC A Series User Manual page 7

[STARTUP AND MAINTENANCE PRECAUTIONS]
Do not touch the terminals while power is on.
Doing so could cause shock or erroneous operation.
Correctly connect the battery.
Also, do not charge, disassemble, heat, place in fire, short circuit, or
solder the battery. Mishandling of battery can cause overheating or
cracks which could result in injury and fires.
Switch all phases of the external power supply off when cleaning the
module or retightening the terminal or module mounting screws. Not
doing so could result in electric shock.
Undertightening of terminal screws can cause a short circuit or
malfunction. Overtightening of screws can cause damages to the screws
and/or the module, resulting in fallout, short circuits, or malfunction.
DANGER
A-6