Is there anything visibly wrong with the driver of my malfunctioning BLF A6 light?
Both wires have dry dry solder joints.
This may not be the cause of your current problem, but it will not be reliable as is.
If you have problems with the low modes, the 7135 chip probably needs to be re-flowed.
(Try to see if the there is solder below the tab on the back of the chip.)
What are the symptoms of the malfunction?
Flashlight won’t turn on at first press of switch, nor second most of the times. When it does, non-click presses scroll through a weird set of modes, with no moonlight but two identical low modes, a mid, and two identical high modes (this is as far as I recall) and the light will eventuality turn off itself.
How to reflow the 7135 chip? Completely de-solder and remove it? I have very basic soldering skills, this is the most advanced stuff I have ever done, but I don’t get any reply from “support” 
Add some liquid flux at each pin and the tab. Then add a little bit of solder to each pin with a hot (750 F) soldering iron.
The flux will make the solder flow where it needs to go.
Do not spend more than 2-3 seconds per pin with the soldering iron. Do not heat it up so much that comes totally free, allow at least one pin to cool down so the chip stays in place.
OK, so, the switch is FRIED.
Maybe I killed it definitively, maybe it was defective beforehand. Any suggestions? Can I cannibalize another light’s switch?
It takes the small Omten switch, not difficult to replace but you have to find out what fried it or you’ll just fry the new one too.
I suppose my iron stayed too long and cooked it. It does not click anymore.
> stuck head
I got mine open by putting a drop of penetrating gun oil (“nano-lube”) and a drop of electronics cleaner/lube (Radio Shack spray can, just a tiny bit) into the groove, drawing it around the whole groove with a toothpick, then leaving the head standing on the bezel overnight. Just a drop. Anything that penetrates into the head will vaporize all over the inside of the reflector and emitter. Don’t overdo it.
At least for mine, I think there was just crap in the threads jamming them — because lots of muscle twisting the thing in a padded vise with padded pliers didn’t budget it at all. Solvent did loosen it up — after leaving it overnight. Then I cleaned it very carefully before putting it back together.
I sourced a switch of the same shape, but orange in color, from a Xeno E03. I hope it will endure the amps, but the E03 supported 14500 cells so I hope it will do the job.
Uh oh... I'm sure they must have improved on that at some point, but that orange switch was the weakest link of the Xeno03 back when they first came out three years ago 
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I got my new tubes today but they didn’t fix the issue. Anybody else have this happen? I thought this was the fix if your light seems to be ok otherwise.
It will fit, but the thin trace from the middle of the board to the switch lead will have a hard time with the 4+ amps that this light is drawing, the corresponding trace on the BLF-A6 tail board is way wider. I would go for soldering a new 1288 Omten to the existing board.
I’m on the weakest possible connection with a rather weak smartphone, and have no PC, would you help me sourcing it from one of the usual vendors?
Oh I didn’t realize that. Perhaps he can bypass the trace like Dale does.
My post #199:
Or try the solder blob/paper clip method.
Penetrating oil, rubber, cardboard and pliers did it. Needed rubber again for the driver retaining ring. No sign of problems. Just wired the springs and added heat sink compound around the driver.
Wow, I’ll sure take you up on that offer. PM coming your way.
FWIW, I tried legoing the anodized and bare versions today. The bare ones were recent, of course, and the anodized ones were from the very first batch.
Everything lego’d fine except the bezels. The bare bezel didn’t work on an anodized head, because the bare threads were too big in diameter and slipped easily over the anodized pill without any need to twist or screw it together. The anodized bezel worked on a bare head though.
At least this much works:
