770e Battery - Sudden death

[TMERTZ]

My battery has been conditioned and was holding a full charge.

I rarely use the battery for more then 1/2 an hour, but yesterday I used it for between 1 and 2 hours. All was good and I was watching the meter off and on. It was at about 25% and then suddenly shut down, reading zero.

Now it won't charge.

My questions are, first is there anything I can do to save this battery?; Second, should I buy a new battery or is it likely the computer?

Thanks

TJM