N5110 Won't start using battery.

Hi there.

I have a Dell N5110 and for some reason it has suddenly stopped starting when only the battery is in place. Nothing happens when you press the start button, no lights, no beeps nothing its just like its dead.

If i plug in the ac adapter and take the battery out it will start, and if i then replace the battery and take out the ac adapter it will stay on and works fine. Also if i re-boot the laptop with the battery in place and ac adapter out it will start again fine. But then later in the day or next morning it goes back to not starting.

When the battery and ac adapter are both in the laptop it shows that it is charging.

The battery seems to have a full charge in it.

I have done the flea power thing but it still won't start after a few hours / next day.

I have run the diagnostic using the F2 key when booting up and it comes back to everything been OK with laptop. I have also ran the Dell diagnostics on the battery and motherboard and they come back fine as well.

The laptop was working fine before this and there is no flashing lights or sounds and the light on the ac adapter is lit when plugged into the mains and also when its in the back of the laptop.

Has anyone any ideas of what else i can try or what the issue maybe??

Thanks