Neither original nor replacement battery will charge. Any ideas?

There is power to pc when plugged into mains but I can't get either battery to hold any charge. I always used to work on battery, only recharging when prompted. The replacement battery has the correct part no. but is a tight fit and was made in China whereas the original I think was made in Taiwan. The original is in place at the moment and I'm plugged into the mains.

Any ideas gratefully received!

Rosemary