TL:DR - the Wii U Gamepad Battery might be bloated and can be posted at https://lemmy.world/c/spicypillows c/spicypillows

All Lithium batteries need monthly usage like checking the oil in your car. If these batteries are stored away for years the chemicals inside oxidate and expand, damaging the electronics inside. PSP battery turned into a pillow as well, and the joysticks become really sticky anyone else noticed old controller joysticks are sticky?