Here's the idea.
This is from an ML25 but the same principle applies.
Sometimes the spring on the tailcap is not enough force to push the second contact point all the way to the LED pill. Tolarences are tight and sometines friction between parts comes into play. You can see in the above post the legs and piston walls in the second photo. They are a tight fit. Sometimes a spring stretch will fix it as that causes more pressure to be applied to the contact point by pushing harder on the batteries.
Now the most likely issue is in the tailcap. I've had brand new never used mini mags fail to light at first then suddenly go to working. This morning the one in the pic stopped working upon reassembly.
Here's why:
Those little contact points were not making a good connection to the internal contact point. I started to unfasten the tail cap and it lit. Viola!!
I cleaned both points and it's now trouble free.
Hope these tips help you avoid spending more money.
If you cannot get it to go and don't want to send it back to Mag, take the head off. Insert a proper sized wooden dowel into the tailcap end and whack it with a hammer. That'll pop the pill out and you can see how it all functions. Apply a bit of lube to the 'legs', then work them into the piston wall a few times. Reassemble and see if that makes the light go again.
Maglite uses stupid simple genious designs, but like anything with moving parts sometimes things go wrong.
I gotta tell ya, there's a great feeling when you can figure out why that non working flashlight won't fire. And an even greater feeling when it fires up.
It makes you jump up and shout "YEAH!! NERDS RULE BABY!!!"
