So about a month ago I was using my flashlight at work with a Fenix 14500 battery. I knew I had been running it for a while but needed the light. It eventually went out and I assume went into "protected mode" in the battery to prevent overdischarging. When I got home I placed it in my Nitecore UM10 charger which supposedly has the ability to revive protected batteries. After a while in the charger it didn't start charging nor say the battery was defective. So I sent the battery off to Fenix and without any words sent me a brand new one. Unfortunately the same has happened to the new one. I'm curious if anyone knows if this is a problem with the battery or possibly my charger and if there is a way I can test/revive it myself.