you should use a wire to connect the cell with the battery tube instead of using the tailcap 
Take the switch tail cap off. Then take a piece of wire and touch one end to the bottom on the battery (on the metal portion) and the other end to the top part of the battery tube. And make sure to touch the bare metal of the tube.
My update on my 5A with mode issues.
Neal responded back informing me he will send replacement head after I sent him a video of mode issues.
I’ve been happy about my BLF A6s and still am after this. Sorry hear you guys aren’t getting handled properly and language barrier is still a hassle with his professional guy. Highly recommend you guys make a video of your issues and send it Neal or the professional guy.
Ok, so I by passed the tailcap and did a basic talcap amp reading.
Got 2.1A on turbo then the voltage began to drop, then started pulsing, then went moon again.
I don't think the tail cap is the issue. :-/
Edit: I placed a piece of conductive metal on the positive end of my battery to ensure better contact and that didn't help either.
I opened a thread in the 18650 flashlight forum so I quit littering up the Group Buy's thread.
My new thread: https://budgetlightforum.com/t/-/35425
Has to be something in the head then. You can take it apart to look for bad solder points but other than that you’ll have to contact Banggood again. 2.1A on turbo is way too low but the leads on your dmm, partially charged battery, etc can account for some of that.
Did you try the 4 mode group just to see if it’s a 7 mode issue?
Also be careful putting any metal on the positive terminal since you can short out the battery.
Hmmm so I never had problems from buying with banggood. … maybe I’m still very lucky hehe
Battery is fully charged and the leads are of decent quality (MASTECH brand).
I can no longer switch modes due to it getting stuck on moon then flickering. It was (and is) in the 4 mode group currently)
Moon doesn't put out any light either, so it's going to make knowing when to switch modes somewhat difficult.
Thank you for the warning about the shorting out, I think I did that before when I used an unwrapped battery on my first light. Now I rewrap them so the positive end can't bridge to the negative sides at all.
Sorry to hear that some are having issues with their lights.
My first of two arrived today unexpectedly, as Really Quickly sent!
Good neutral tint.
What a great driver and UI.
Well done to all involved in making this happen.
It instantly became one of my EDC lights! How good is that? :bigsmile:
I’ll wait and see if the even warmer tint one is equally well constructed etc.
It’s almost established that 7135 chip is the culprit: Either defective 7135 or bad solder joints in 7135 “legs”.
I sincerely hope “send replacement head” mean the 7135 problem fix.
Wasn’t the 7135 issue just related to no moon or similar output levels on the lower modes? Just asking….it’s hard for me to look through this massive thread to recheck my faulty memory 
Since it’s not working I would take it apart and check the solder joints since there’s nothing to lose.
A defective 7135 or bad solder joints in 7135 legs wouldn’t explain all the issues CircaM reported. There has to be a connection issue somewhere in the head, maybe LED- wire solder joint or the tube is too short not making proper contact to the retaining ring at the driver side.
ToyKeeper is the one giving most of the possible causes. Maybe somebody goes thru TK’s posts and compile the causes suggested.
Has anyone given Neal or Professional Guy or Manker a checklist?
Items to be checked and how (flowsheet form?)
Particularly for replacement lights — it would be good to know they have been checked, not just replaced out of the bin “send Charlie another light”
This might be useful for those receiving lights as well —
1) Does it light up? Unscrew tailcap (note if it is extremely loose — is this a failure?)
Insert charged li-ion cell, positive end goes into the tube
Replace tailcap.
[insert here a detailed check running through the button sequences — ask The One Who Knows This how to check it, maybe how to reset it, and define what is a failure]
Quoting Bugsy in the CircaM thread:
[Remove the cell]
If passes, go to
2) is the bezel stuck?
With one hand, hold the light lens-up, tail down, gripping the part with the BLF initials on it firmly
With the other hand put the tip of the index finger on the lens and press down firmly but gently (it’s glass, don’t break it)
With the thumb and middle finger wrapped around the bezel, try to turn the bezel.
— If it turns, continue pressing down on the glass, and re-tighten it (the pressure avoids having the O-ring pop out behind the lens, or the white spacer lift up off the emitter)
— If it does not turn, this counts as a failure. Set that light aside.
If so it might help to post that here as well,
“If passes, go to
2) is the bezel stuck?”
“— If it does not turn, this counts as a failure. Set that light aside.”
.
I fail to see the logic in this…
If the light works, why take the head off, possibly damaging the emitter?
I received mine a couple of days ago and everything works fine. - Since it works fine, I want to keep it that way, so the only threads I have turned is the tailcap to put a battery in it. - Yes they are a little loose, but like I said - The light works fine.
If a modder wants to change something, that I understand, but for the average guy - If it ain’t broke, then why are you trying to break it?
Thanks,
-Chuck
I’m guessing that was because one of the things that are wanted on the GBs is to not have the threads threadlocked (Loctite/glued)?
The low current is likely due to a cold solder joint that others have seen.
Mine is working as-is so I don’t want to chance it just yet by taking things apart.
But with the pip in the pill, the smashing of the emitter, and the cold solder joints all noted already, this light just might be worth rebuilding at some point.
I’m getting ~340ma. I’m going to assume that this is the AMC7135 driving the constant power for this mode.
The bezel stuck / “head stuck” on mine (and some others) was on the same light with the O-ring being popped out of its groove.
Could be they used too small an O-ring, but I don’t know if that’s an issue.
Or they assembled it without noticing the O-ring had slipped and the extra pressure jammed the bezel.
Since solvent and time fixed both problems overnight, I’d guess the latter — for the one I had.
But for a stuck head and no visible O-ring, I’d guess there’s crap in the threads jamming it. Since the stuck ones were really stuck and the finger-pressure method saves wrecking the emitter, I recommend it be well understood.
If yours is stuck and you don’t care, blessings upon you. Most of us would like to be able to open what should open, and close what should close, and replace anything we like.
My suggestions for a checklist are for the people assembling the light.
“You don’t know how to build a tool until you know six ways to do it wrong …” to paraphrase J. Baldwin of the old Whole Earth Catalog