Lenovo THINKPAD E40 Hardware Maintenance Manual page 17

DANGER
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.
9
Safety information