My Nitecore EC21 is screwed up and I don't know why

Long post full of probably too much detail, just read the first sentence of the second paragraph below and then skip to the bottom half if you don't want to read it all.

I've had this light for roughly a month and a half now and ever since I got it its become my constant EDC light.
I'm constantly using this light every day and 90% of the time I'm using the medium 100 lumen mode, most of the time I'm using a olight branded 3400mah 18650 and when that's in the charger a nitecore branded 2300mah 18650.

Used it multiple times today without issue and the last time I pulled it out of my pocket, hit the switch and nothing happened.
Have a small nub of silicone I glued to the power button so its easier to find when I pull it out of my pocket, occasionally it turns on in my pocket and since its been several days since I charged the battery I just assumed it died so I put the battery in the charger and swapped my nitecore battery in.
It still didn't turn on, concerned now but just in case I put in a cheap ultrafire 18650 that I use for my no name lights.
Still nothing.
Offset red led does not flash to indicate battery voltage when I install the battery like its supposed to.

So now I turn to button mashing and taking the battery out and putting it back in, 90-95% of the time nothing happens but twice when I held both the power and mode button down after several seconds the light would turn on for an very brief instant.
Its hard to tell for sure since its so short but the two times it happened I think it came on in the turbo mode.
Also very rarely, occasionally when I held down the mode cycle button for about 5 seconds or so it would turn on and stay on as long as I held the button down, it comes on in turbo mode.
First time I got it to turn on by holding down the mode switch it stayed on for about 7 seconds until I accidently let go of the switch, many many tries later I got it to once again come on and it stayed on for roughly 15 seconds until, still holding the mode button I used another finger and pushed the power button and it just shut off.
Many button presses later I got it on again for roughly 20 seconds until my finger slipped.

And finally once more after more than 50 attempts by pressing the mode button down I got it to turn on and kept it on for roughly 45 seconds.
At that point it was getting warm since its on turbo and I once again pushed the power button and nothing happened, it stayed on.
I let go of the mode button, it continues to stay on, I use the mode button and it cycles through all the different modes properly, accidently confirmed the strobe mode works.
Turned it off and on without issue multiple times.
No clue what the stupid thing is doing but decide to shut it off and wait a couple minutes to see what happens.
Waited roughly 5 minutes and hit the power button, nothing happens.
I once again have a dead flashlight and now sore fingers from holding that button down so many times.

Its been a fantastic light until now without issue, I've dropped it a couple times but its been more than week since I last did that and it never fell from more than 3 feet up.
Spring in the tailcap is fine, no issues with the positive side I can see either.
No visible damage to the light, anodizing is worn on edges but that's because I carry this light, a small aa backup light, my wallet, pocket knife and keys all in the same pocket.
It worked fine the last time I put it into said pocket.

I'm tired of screwing with this stupid thing and will contact nitecore when I have the chance but I wanted to ask here if anyone has had issues with this light or anything similar with another nitecore light.

Thanks.

This may sound dumb, and I am pretty sure you are aware of this, but by some crazy chance, did you lock it out?

I had something similar with a Nitecore EA41 I had awhile back and thought my light was broken. It wouldn't turn on or do anything, it sometimes would briefly flash then shut off. I read the manual and tried mashing every button like you and didn't have any results. As a last resort I took the batteries out, cleaned the threads and left them out for a minute or so to "reset" anything and cleaned the threads well. Put the batteries back in and light turned right on. Not sure if it was an issue with the threads or the circuit, but whatever it was taking the batteries out for a minute and cleaning the threads fixed it. Maybe see if that'll work for you, I've had no issues since.

Str8stroke said:

This may sound dumb, and I am pretty sure you are aware of this, but by some crazy chance, did you lock it out?

Click to expand...

That was one of my first thoughts and I checked multiple times but no it wasn't locked.
Little red led never flashed any of the times when it should have.

snowlover91 said:

I had something similar with a Nitecore EA41 I had awhile back and thought my light was broken. It wouldn't turn on or do anything, it sometimes would briefly flash then shut off. I read the manual and tried mashing every button like you and didn't have any results. As a last resort I took the batteries out, cleaned the threads and left them out for a minute or so to "reset" anything and cleaned the threads well. Put the batteries back in and light turned right on. Not sure if it was an issue with the threads or the circuit, but whatever it was taking the batteries out for a minute and cleaning the threads fixed it. Maybe see if that'll work for you, I've had no issues since.

Click to expand...

Left it without a battery for a weekend, cleaned the threads and made sure all the contacts were good but alas, it would not come back to life.

I bought this from Amazon warehouse deals so there is no warranty on it, was only $30 and it came with a 3400mah 18650 so I'm not terribly dissapointed.
I'll just try to fix it myself and see what happens.

Click to expand...

On the EC21 the battery tube can unscrew from the head itself which is quite convenient.
Solder from the one rectangle is contacting the button in the middle but it was like that out of the box so I'm assuming its not a issue.

Click to expand...

Like another nitecore flashlight I have they used red loctite on the lens threads.
Soaking the head in a cup of hot water from a keurig machine for a couple minutes and it came right off.
The reflector seems to be pressed into a chunk of aluminum.

Click to expand...

Was trying to go in from the top but that doesn't seem to be possible.
The other nitecore flashlight I've disassembled had a aluminum disc pressed into place that the led sat on that functioned as the heatsink, I have yet to remove stuff to get a closer look but I don't see a line between the sink and the walls of the tube.
I think its machined into the tube itself and I'm not gonna get anywhere from up top.
Its hard to see but in the shadow in the top right corner of the last picture there is a small nub of silicone that was sitting there when I pulled the reflector out.
Not sure why and I don't see anything it could have come from.
Interestingly enough inside the head there are bubbles in the coating scattered around in the anodizing.
And in one spot the coating has turned blue with even more small bubbles in the blue area.
Like it got real hot in that area.

I'll do some more work on it some other day when I've got a break from work.
[E] discolored area is blue not brown sorry.

Curious to see what the results of this are, the solder connections look good that I can see. Could be something with the circuit board and/or the switch itself.

I work very slow but I'll update this thread whenever I do something.
For now a bit blurry yet better view of the grayish blue discolored spot.

Removed the led, heat sink is part of the head and is a dead end.

In the very center there is a dimple/indent from when they machined it, not that worried about it but I might fill it in with something.

Removed some solder from the slots and other two connections on the board but my finest tip I'm using that actually works well doesn't fit in the slots fully so there's still stuff I can't get out.
I know nothing about what circuitry is behind the board or how this is held in place so I have no interest in pumping a lot of heat in and damaging something.

If anyone has disassembled a nitecore head like this or knows of a thread about a head like this I'd love to know about it to see what's been done before because I am flying blind right now.

Decided to resolder everything, solder a wire to positive terminal and yank.
It popped out, there is glue residue around the edges of the board which is how it was held in place.
Here it is:

Massive glob of solder on the positive wire that is making contact with other components on the board although that was probably from me.
Will clean it up regardless.

Other side.

Overhead

They came very close to going through in the middle when they machined it.

Thats all for now.
Will clean up around the negative wire and test for continuity in all of those wires and see if anything's funky later.

If the head turns out to be dead...

Keep the battery tube and end cap, buy an EA11 or MT10A with the 960 lumen head, and AA/14500 battery tube.

It should be able to interchange the EC21 battery tube and cap onto the higher-rated head, with an 18650 cell (especially a newer NCR18650GA 3500mah) inside, and have much higher run time than EA11/EC11, with FAR higher output than the sub-500-lumen EC21 head.

A nice high-output white and map-reading red LED head, with choice of 18650, 14500, and AA in a pinch. Might or might not be able to handle the voltage of 2xCR123 cells in the 18650 tube, though. The circuitry may or not be set up for 6 volts, rather than 1.5-4.2 volts.

If the 960-lumen EA11/EC1/MT10A/MT10C head can handle 14500IMR or 18630IMR cells, an 18650 at the same voltage should work, and just last longer.

I kind of wish EC21 battery tubes and end-caps were sold as accessories to do just that. They likely don't sell EC21 that way, to keep an edge for MH20 to be the 18650 light of choice in that segment.