Not sure why it stopped lasing when you were focusing it, but with this tiny build, it needs a small tipped dual prong, (like a 'bent nosed' pair of tweezers), to reach in and get the pill tight on the final assembly...
Otherwise, the module could 'twist' on you. And you can't let that happen!
Not sure this is what happened, but obviously you can't let the module twist, because the wires would twist. Plus, the heatsinking would not be as good if the pill was not tightly against the module/sleeve...
I'm sure Dave knows that though, so hopefully it's just a connection issue with the 'thicker' battery getting stuck inside the tube, and not getting a good connection.
I don't like those new protected 10440's. They are too thick, and also too long for most AAA hosts...