Lenovo M490s Hardware Maintenance Manual page 30

• If the voltage is more than +12.0 V dc, discharge the battery pack until the voltage becomes less
than +12.0 V dc and then recharge the battery pack. If the voltage still is less than +12.0 V dc after
recharging, replace the battery pack.
Note: Recharging will take at least three hours, even if the battery status indicator does not turn on.
5. Replace the system board if the new battery pack is not charged.
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Hardware Maintenance Manual