THIS THREAD has user manuals for a lot of the lights we talk about.
Somewhere about a quarter mile down is the Narsil manual. Is that the one you’re looking at?
FYI - when it says “display firmware number”, it’s talking about flashing a certain number of times. As an example, in the battery check mode, to say you are at 3.5v, it will flash three times, pause, then flash five times, pause a bit, then do it again.
Hmmm… I don’t see anything about a factory reset in a quick cruise through the manual. Some lights will reset if you unscrew the battery tube, hold down the power button, screw the tube back on, and not let go of the button till it goes through a flash cycle. I can’t say if that will work for you, but it’s worth a try.
Hmmm… Are you sure your light has Narsil and not Anduril?