Lenovo IdeaPad U300s Hardware Maintenance Manual page 26

Lenovo IdeaPad U300/U300s/U400 Hardware Maintenance Manual
Perform operational charging. If the battery status indicator or icon does not
light on, remove the battery pack and let it return to room temperature. Reinstall
the battery pack. If the charge indicator or icon is still off, replace the battery
pack.
If the charge indicator still does not light on, replace the system board. Then
reinstall the battery pack. If it is still not charged, go to the next section.
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