Sofirn if25a won’t turn on

Hi everyone. Long time lurker here. I dropped my if25a and now it won’t turn on but the switch remains lighted. I’m just looking for advice on where to start. I’m guessing something got knocked loose. I’ve never modded or repaired an led light before. I used to hotrod mag lights but basically just copied well known mods. Any help with some simple troubleshooting tips would be great thank you.

My first guess would be the actual switch or wire connections to it. The LED on it would have a separate wire so the fact that it’s on doesn’t mean the switch is OK. I don’t own one of those lights but by looking at pics it looks like you can unscrew the retaining ring around the switch. If you can, remove the rubber switch cover and see if you can short the switch connectors (without shorting the LED).

Might be hard to test but I would suspect the possibility of cracked solder on the brass button contact or perhaps something on the board itself (on the other side where you can’t see without disassembly). In this post there are some borrowed pics of the driver…looks like a lot of potential for issues with hard drops: [Review] Sofirn IF25A flashlight: $34 (discount code available) with 21700 cell, 3800lm, USB-C, Anduril [pic heavy] - #39 by 80T

I’d make sure the tail spring is still snug and where it needs to be, too.

If nothing else, Sofirn is usually really good about sending parts (or sometimes an entire new light). If this model driver doesn’t show up in their aliexpress listing for drivers, just message them and they can let you know a price (would assume this one might be a little more expensive). Changing the driver isn’t too hard but will of course require working from the front end of the light, desoldering the led wires, removing the switch (no desoldering there), and poking the driver out the bottom using a pick/probe. Fiddly, but if you can do basic soldering of wires to contacts, not a bad job to do.

Oh, also, check the positive end of the battery to be sure that it didn’t simply crush inwards and can’t make contact…doesn’t look real plausible with the giant brass contact pad on the driver, but a simple inspection to do.

I doubt the problem is anywhere in the tailcap since the aux leds in the switchboot are lighting up.

The issue might be one of the driver wires on the star desoldered. Checking should be easy assuming the bezel isn’t glued. Just unscrew the bezel, lift off and remove the lens and optic and then check to see that both wires on the star a securely soldered down. If one is loose, then that’s the problem.

Thanks for all the suggestions. I’ll report back if I get it figured out.