Battery capacity still shows 0% even after 20 hours of charging

Q: Battery capacity still shows 0% even after 20 hours of charging, and the laptop immediately shuts down when AC adaptor is unplugged, what’s the problem?

A: The first thing you need to do is check the contact between the laptop and battery,
because if the contact is not good, even the communication data between them is read,
the battery cannot be charged. Since the laptop battery slot may become disfigured after
long period of use while the battery plastic casing is designed according to new laptop
specification, it would cause contact problems. Under such circumstances, please take
off the battery and put it inside the laptop for several times to ensure better contact.
When you hear a sound CLICK, it basically means the contact is good. Try more times
and the contact problem can be solved, especially for IBM laptops.