Use the size 0 screwdriver to loosen the screw on the DS Lite's battery compartment. The compartment is on the back of the unit. Remove the cover.
Take out the DS Lite's battery pack. Carefully insert the *** of the screwdriver or your fingernail into the tab at the top of the battery pack compartment and pop it out.
Leave the battery pack out of the unit for at least 10 seconds.
Replace the battery pack. Line it up within the battery compartment and push it back into place.
Put the battery compartment cover back on by sliding its tabs into the slots on the unit. Push the cover back into place and tighten the screw with the Phillips screwdriver.
Turn on the DS Lite. If the unit has reset, a screen will prompt you to adjust your system settings.