This battery charger is designed to charge battery packs APS 5 used with the following thermal imaging monoculars:
Axion XQ35
Axion XQ35 Pro
Axion XQ35 LRF
Axion XQ35 Pro LRF
Axion XG35
Axion XG35 LRF
It needs a charger made for APS 5 packs, and this is that charger. The pack has its own shape and contacts, so a loose-cell 18650 charger won't hold it. A separate dock lets you charge a spare on the kitchen counter while the Axion is out in the field with the other pack.
Leave it on this charger at room temperature for a good while first, because a deeply drained lithium-ion pack can be slow to start taking charge. Skip tricks like jump-starting it from another battery. If it still won't charge, the pack is done and needs replacing. Keep in mind that batteries are not returnable.