I have an older Intel NUC6i3SYK. The CMOS battery was dead, so I've replaced it, but I'm still getting a CMOS error on boot.

The original CMOS battery connector looks like this:

The replacement battery, from PBTech, looks like this:

It's a bit hard to tell from these photos, but the red wire is on the right of the top image, but the new battery has the red wire on the left when installed. The connector is not reversible so it's not like I've put it in the wrong way.

Is there such thing as different polarities for CMOS batteries? It is possible that I have purchased one with the 'wrong' polarity, and this is why isn't not working?

In my searching I've not found any evidence that CMOS batteries are sold with different polarities, I would have thought that they are all the same (particularly those with the same plug on the end)?