New CMOS Battery 2.79V, a Dud?

My 2009 netbook wouldn't post, so I dismantled it to replace the "RTC battery". The battery measured 2.9V, which is below the 3.0+V threshold, so I thought, "ah hah, I just need to replace it". I went on eBay, found a reseller that's sold plenty of batteries and finally received the battery today. (Took a week.)

Just as a double check before putting everything back together, I tested the voltage and it was even lower, 2.79V! Did I get a dud? Or does it need some charging first? The battery is an ML1220, which says Rechargeable on the battery itself.

Recharging it might require assembling everything again and I'd rather not, unless I know recharging is the only problem and the low voltage is fine with a new battery.

Thanks!

 

I reached out to the eBay vendor and they said if it's above 2.7V, it should be good. My old battery was 2.9V, so I don't know why it wasn't working, unless the battery holder somehow became disconnected. They said they would replace if it dropped below 2.7V, though what a hassle it'll be to reassemble everything and then find out it needs replacement.