Is my battery the problem?

Hi guys,

I have a Macbook Pro Retina, which yesterday stopped working when operating on battery alone and requires the power at all times. I have had it for 2.5 years.

It won't switch on immediately, however, with the power adapter. I have to hold the power button for 8 seconds, then attach the adapter. It then fires up, with the fan going crazy.

If the adapter comes out, it immediately goes dead.

When I go to check the battery diagnostics in the power section of the system overview, it's not even acknowledging there is a battery and shows no information at all.

My question is, while I obviously need a new battery, do you think there's more to it than just that?

Thanks,

Betty