Love the pup & thanks for the help.
Because I had one dead battery and two Thins, I was able to isolate that it wasn't a controller or charger issue. The battery showed 0 volts on the multimeter.
Here's what I think the problem is... on a whim, I flipped the switch on and off a dozen times (because for a fraction of a sec after I turned it on, I would get my LCD to react). By doing that, it stayed on, which leads me to believe I have a defective switch on my battery. Has anyone else experienced this?