Why my Lenovo Flex 14 keep saying "plugged in, not charging"?

Maybe it's time to remove the Microsoft ACPI Compliant Control Method Battery,remove the Microsoft ACPI Compliant Control Method Battery and allow Windows to scan your computer for hardware and reinstall the drivers needed to manage your battery's power. The notebook should then indicate that the battery is charging.

In Windows 10 or Windows 8, hold the Windows key and press the 'x' key to open a menu in the lower-left, then select Device Manager. In Windows 7 or Windows Vista, click Start and type device in the search field, then select Device Manager.
Expand the Batteries category.
Under the Batteries category, right-click the Microsoft ACPI Compliant Control Method Battery listing, and select Uninstall . 
WARNING: Do not remove the Microsoft AC Adapter driver or any other ACPI compliant driver.
On the Device Manager taskbar, click Scan for hardware changes.
Alternately, select Action > Scan for hardware changes.

Brand new LENOVO Flex 14 Series 14.4V 2000mAh laptop batteries

Voltage: 14.4V

Capacity: 2000mAh (32Wh)

Battery cells: 6-cell

Chemical: Li-ion

Battery Color: Black

Condition: new original battery

Warranty: 9 months