Laptop won't detect battery.

I've had several problems with the laptop I bought only 4 months ago, and I've received very little help towards rectifying all my problems.

The most recent problem was that the motherboard already had to be replaced due to damage caused by the delivery company.

Now that I've received the replacement motherboard and changed it for the old one, it won't recognise or charge my battery, which still works fine, charges from the old motherboard and gives it power.

Any post I've seen points to there being a fault with the motherboard being on its way out. This is a brand new motherboard. The battery and AC adapter are both working perfectly. What is the problem now? 
Thanks in advance.