Batteries are fully charged and inserted correctly. Green light doesn’t turn on
Ok, the switch LED is a very basic function, The most likely reason for it not turning on is that the driver is not getting power.
I would check the ends of the carrier to make sure it has the correct voltage. Then make sure the driver is screwed down properly. Also try pressing the carrier down onto the driver manually without the battery tube installed and see if it makes contact like that and turns the switch LED on.
Oh, also make sure the carrier is installed the correct direction, the “button top” end needs to face the driver.
If none of that works, the next step is to manually apply voltage to it with wires if possible, positive to the center contact and negative to the retaining ring for the driver.
Like this.
You press the carrier manually so it makes contact. Make sure the screws on the carrier are not loose.
Since it’s a 3v led, only one battery is needed.
Yeah the flashlight is dud. I don’t know where to send it to get repaired or replaced. Still waiting for response from Neal
I tried the carriers from the GT70 with the greens cells, the led switch turns on , but the flashlight won’t turn on
Uh oh
That is really strange that not even the switch LED will turn on. Something would have to be seriously wrong for that to happen and shocked it would of made it threw QC.
I can fix it assuming I can get any needed parts from lumintop, which could be hard right now due to shipping delays from china. I have worked on a few other lights for them over the years.
I actually have a few GT90 conversion kits that I talked them into selling me on the way now. Possible the kit would have the parts needed to fix it.
Neal has been super busy, seems all the factories over there have been pressed into service making masks and other such items and are only able to work on flashlights at night after hours. You can also try contacting Leo@lumintop.com.
If you want to just send it to me to look at, send me a PM and we can go from there.
When did you do that? Before or after you had issues? That would of instantly killed the LED as the GT70 carriers are 12v and the GT90 is 3V.
In this case there is nothing I could do right now as the LED will have to be replaced and hopefully it did not also kill the MCU.
If you used the GT70 carriers on the GT90 you killed the light yourself (Chibim did kill it as well using the wrong carriers)
The voltage of the GT90 is 4,2V (cells parallel) whereas the 70 needs 3S1P (correct me if I’m wrong)
The GT / GT70 is 4S (so 16.8V fully charged).
Interested
Well, after a lot of shipping hassle and ending up having to ship it express just to get the package past customs;
I am now in possession of a few GT90 conversion kits for either the GT or GT70.
They include:
MCPCB with pre-installed SBT-90.2 LED
GT90 Texas Avenger driver
2x GT90 3V carriers (CAN NOT USE past carriers, they are 12v)
Centering ring (comes with the stock ring right now, I am looking into 3D printing better fitting rings once the shop with the printer opens back up)
Switch pre-soldered onto the driver
I only have a few of them and doubt I will be able to get more, particularly with the hassle it was to just get these out of china much less talking them into selling me them in the first place lol.
They will be on a first come, first served basis.
Send me a PM if interested.
TA, I cant believe you pulled it off! 
PM sent.
I would be interested in a better centering device when you get around to it too
Thanks T/A
It was not easy, I started trying to get them 3 months ago now and they just showed up yesterday to give you an idea lol.
The 3D printer is not set to re-open for at least another month last I heard. So it could be awhile. Send me a message then if I forget.
The last GT90 conversion kit sold a few days ago BUT seems that lumintop is in need of some cash and are willing to sell me a few more out the back door.
I am putting together an interest list for those that want a GT90 conversion kit for the GT or GT70 (same kit works in both).
If you are interested send me a PM quickly as the number of interested parties will determine how many I get.
Hey Ace… got my SBT90.2 kit today…nice packing job… everything looks good.
I see what you mean by needing a better/real centering device 
… I have a couple Idea’s…
If you are careful when you tighten the head down, it puts enough pressure that it should stay centered unless you really bang it.
Long term though I do want to make some custom centering rings that fit better though but the 3D printer is still closed at least until next month last I checked.
In other news, I will be placing the order for the GT90 conversion kits on Monday. While I plan to order a few extra kits I can’t afford to be left holding a bunch of them.
So If you are interested, let me know.