Semi destroyed NDI

Let me start off by saying I feel like an idiot, I inserted an IMR 14500 backwards into my NDI, I smelled the distinct odor of something electrically wrong. Upon removal I noticed the battery cover was singed, but more importantly one of the black rectangles on the LE was burnt. Interesting thing is that the light still functions normally on a 14500 but doesn't work at all with a regular AA. Anyone have any ideas what happened and can it be repaired, is it safe to continue using the light

Thanks for any input.