In the 2nd pick of the Concord 4 panel, it looks like that might be a 2GIG takeover module in the bottom right corner of the pic partially off the screen. Can you confirm?
If that’s the case then it would be the battery in that pic (Universal Battery AMG type) that you need to replace. The sensors themselves don’t use power or have a battery but the takeover module does.
Here’s a general battery guide that has some links on where to find them.