Lenovo ThinkPad L412 Hardware Maintenance Manual page 12

Though the main batteries have low voltage, a shorted or grounded battery can produce enough current to
burn personnel or combustible materials.
DANGER
Unless hot swap is allowed for the FRU being replaced, do as follows before removing it: power off the
computer, unplug all power cords from electrical outlets, remove the battery pack, and disconnect any
interconnecting cables.
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Hardware Maintenance Manual