That is a very weak cell, so that’s not the cause. Going white, blue, purple is a sign of overheating. If this happened over a few seconds my guess would be there is not enough solder between the led and the mcpcb. It could not shed the heat fast enough. If it took over 10 seconds the mcpcb might not be making good contact to the flashlight body. Not due to a grain pattern, but like a foreign object not letting the mcpcb sit down flat. One side might be lifted up.
Hmm! Yeah, was in the space of 1-2 seconds, maybe my reflow was garbage.
Might buy another one and be suuuuper sure I do it right.
So this was not a factory led and mcpcb?
Sorry if you mentioned that, I can’t remember.
Was an SST-40 de-domed from KaiDomain - I got it on a 20mm MCPCB but no way that will fit under the reflector, so I reflowed it to the 28mm it comes with. After that blew, I swapped it back to the stock NW it came with, and it’s been fine (albeit slightly off-centre due to my idiocy with the gasket).
Right,I CHOSE option 1 and there is NO step down.So which step down is it is since you are saying we can not have both[timed/temp.]?
It certainly acts like the TIMED step down is disabled to me.
This has been beaten into the ground!
s. If I want to ask Tom, since he designed the firmware, that is my business. To me that makes more sense than asking you or others. 
In this case I don’t think they even used what I sent them. The firmware I sent them was the S43 firmware that was just meant for testing a prototype and then tweaked for this host. When I sent the firmware they were planning on using the S43 driver in this light.
After that I never heard back from them. I was not even aware the light was still being worked on until someone sent me a link to this thread. I literally had zero involvement in this light development outside of that initial firmware that was just meant for testing. Although they made heavy changes to the hardware design, I have no idea what happened with the firmware.
The S43 and thus the firmware I sent most certainty uses temp step down by default. So I have no idea what is going on with this one.
I am also talking to my contact about getting link added to the listing for these lights, once again stuck at the getting the file hosted part of that issue. They don’t have a website and banggood is not easy to get to someone that knows how to do this….Always something. He has no problem adding the link, the issue is getting a link to add.
After reading TA’S and Toms comments it is quite clear what they have printed on the manual “May” not be the firmware that this light has,at least for the step downs!
I have had many lights with no step down at all or default after 20 minutes. By me choosing “1” -DISABLE, I am convinced the Timed step down is deactivated. That is exactly how the light behaves from turn on until 20 minutes when I change the battery. Very slow and gradual decline in output as battery depletes which is barely noticeable by eye.
Gentlemen , that is my story, belief and experience and I am sticking to it. 
I don’t care what Jason says! 
You could just be thankful that others are trying to provide input instead of waiting for Tom. Tom can still answer you as well if he feels the need but so far he has not…
You can only have one or the other, separately. If Timed is selected it’ll be Timed without Temp. If Temp is selected it’s only Temp that determines the step down. If you disable it then there’s no Timed or Temp step down.
You are correct that timed step down is disabled. The default temperature step down is also disabled. Mine is definitely still in the default temperature step down mode as it runs for about 7 minutes the first time on then shorter times after that. I am thinking about leaving it on but upping the temperature . Just in case it gets accidentally turned on and starts a fire. I leave my lights on the table and my 3 year old grand daughter could decide to turn one on. Step down will save the battery also.
You could always enable lock out before leaving it on the table. 4 fast presses from Off.
Wait - wut didn't I answer? I'm confused - too much to keep up with - Sorry, bizy @work and trying to keep up with couple BLF things goin on...
What is true is those 3 options: can only be disabled, timed, or temp -- no combo of time and temp.
I'm trying to find out how the light shipped for sure - factory setting. The manual says temp stepdown, not timed. Details are many times hard to get from the China manufacturers.
I could/should run an independent test on my 2 FT03's to find out as well, but that could be tricky if it's set for temp stepdown at a high value.
I think if you factory set the degrees in C, say for 55 for example, there could be a +/- 15 degree swing or so.
Update: Ok, just checked the source code TA posted.
It is configured for:
- temperature stepdown at 55C, with the temperature cal offset set to -3. This is assuming Mateminco engineers didn't change anything - probably didn't.
Again, This can vary up to 15C up or down per flashlight, hopefully more likely +/- 5C.
This is what is confusing with many people saying things in different ways!
IF DISABLED means there is NO timed OR Temperature step downs in active use, then HOW can there be no combo of time and temp step down disabled?
I didn't say "time and temp step down disabled", I said "time and temp", meaning timed stepdown and temperature stepdown. Both cannot be enabled at the same time.
Yeah, I give up. 
good!
Ok gentlemen,this is CLARITY explained by Professor WOLFDOG!
Here are the OPTIONS, CLEAR W/ NO CONFUSION! 
1. DISABLE - This means their is NO step down whatsoever. BOTH Timed and Temperature are DISABLED.[Wolfdogs preference] 
2. Timed step down CAN be disabled -SOLO
3.Temperature step down CAN be disabled- SOLO
4. Temperature and Timed Step down can NOT be activated at the same time! One or the other.
Seriously, stop being rude.
This is a public forum so play nice
How was this not clear to you?
You ask for Tom’s input and you were still confused lol
Yh it was pretty easy to understand for me
Oh boy, maybe this helps, as pretty much exactly what the manual says:
There are 3 output stepdown options:
- Disabled - no output stepdown
- Temperature based stepdown (default temperature is 55C, but the user can set it)
- Time based stepdown, choices are 60 secs, 90 secs, 2 mins, 3 mins, 5 mins or 7 mins