One of my EmonTH’s just stopped transmitting for no apparent reason - Battery level was fine, then it just ‘went away’. Upon opening it up, I found that the battery holder seemed a bit loose - turns out the terminals separated from the board and ripped the pads right off the board. I might be able to fix it, but one of the pads on the bottom had a trace going to it (looks like it supplies power to the Atmega), so bridging that to the pin might be a challenge, as well as trying to solder to the pads on top.
Now, to be fair, it’s probably because my daughter got ahold of it several times and was playing with it, so there’s no telling what kind of bumps it took, but it would be a really good idea (IMO) to secure the holder to the board a little better than with just the terminals - a couple dabs of hot glue, for example - so that a fall that would otherwise be harmless to it doesn’t kill it.