Lenovo B490 Hardware Maintenance Manual page 38

If the voltage is still less than +11.0 V dc after recharging, replace the battery.
4. If the voltage is more than +11.0 V dc, measure the resistance between battery terminals 5 and 7.
The resistance must be 4 to 30 K Ω.
If the resistance is not correct, replace the battery pack. If the resistance is correct, replace the system
board.
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Hardware Maintenance Manual