There are several factors why a pack might not be recharging.
Power Packs need to be recharged every 6 months if unused, to maintain their integrity.
If you have recharged in the last 6 months, was the pack connected to furniture that has a USB port, LED light, Lit wand, handheld controller, lit cup holder, etc.? Is the furniture used on a regular basis (at least 2-3 times a week)? Did the interactive low power alert sound when you tried to operate the furniture?
If yes, the pack needed to be recharged. If you waited over 2 weeks to do so, the pack could have consumed the power reserve and pack entered terminal shutdown.
If not- A system that has a constant draw can drain a pack down into the hard shutdown mode. If you waited over 2 weeks to recharge, the pack may have consumed the power reserve dropping it below its functional range resulting in terminal shutdown.