I’m not aware of any way to re-attach a dome to an LED. But even if you could, the LED would still not work. It seems somehow the dome got pulled off and when it did, the LED wires got detached and that’s the reason why it’s not working. A new LED will need to be reflowed onto the MCPCB.
Yeah,I figured it was not repairable.Thanks for the reply.
My guess is it didn't get fully attached in manufacturing and the slightest jar in shipping had it come off.
I received a Sofirn SF11 from Amazon with the LED lose in the reflector but it was easy to reflow that one.
Maybe my wording was bad.The LED wires were OK.I removed the wires from the MCPCB because the driver came wire wires attached and it seemed much easier to use the 2 driver wires than the 2 MCPCB.wires.
I'll just order another XP-G3 LED.
The S2+ with a triple XPL Hi gets quite hot in a few minutes that I can only hold it with 2 fingers on the tail cap.It was a lot of fun building it in a red host.
I meant when the dome came off, it probably also disconnected the wires in the LED. They are very fragile.
Glad you are able to reflow LEDs and repair it yourself!
https://flashlightwiki.com/Cree
Scroll down a little and you can see the bonding wires embedded in the silicone dome.
Those are the wires that have probably came off with the dome.
Thank You all.I ordered a few XP-G3 replacements.
The triple S2+ is a beauty to behold.in the S2+ red host
The triple XPL Hi V2 1A is something special.with Hoop's copper pill,Dr Jones H17F driver, Carclo 10507 powered by a Samsung 30Q
Now the hard part of learning the Dr Jones firmware.
IMO the best S2+ bang for the buck is the SST40 1800lm 5A with smooth reflector,driver locking ring and bypassed springs on Banggood for $13.99
I build a few, I use one with a 18350 body as my edc.
Triple Luminus SST-20 (3500k) 7$ include optics http://kaidomain.com/Flashlight-DIY-and-Tools/LED-Emitters-or-LED-Star-on-PCB/Triple-LED-On-PCB/Triple-SST-20-LED-Emitter-with-20mm-x-1_5mm-Copper-PCB-Parallel-w-optics
Two copper base plates a 16 and 20mm ($1,24 from Fasttech) Instead of the 20mm base plate you could also use a second glass lens.
Nanjg AK-47A driver $1.93 from Fasttech.
I desolder one 7135 regulator and put a FET on it. (comfychair-inspired quick+cheap+lazy single-sided 17DD FET-driver (poor man's nanjg92)) (The FET that I uses are from a old pc mainbord. )
Flash the driver with blf-a6 firmware.
Ok,I received XP-G3 replacement LED and reflowed it onto the MTN Triple MCPCB
There was enough solder on the MCPCB so I only used flux.
The asterisk on the MCPCB denotes negative side for LED
After the reflow I cleaned the excess flux from the MCPCB with a Q-Tip and 100% alcohol.
All 3 LEDs lit up in continuity test with my voltmeter.
Thanks again for all the help!
Still wondering why people prefer the S2+ over a Jaxman E2L, which is also sold as a host
I'm guessing you own a Jaxman?
Probably name recognition,wider availability and the 11 or so color options.
I never heard of Jaxman
Glad you got it to work whatsthepoint! 
Unfortunately the JAXMAN E2L host is no longer available: JAXMAN E2L HOST. 
I have 2 of them and they certainly are great triple hosts/flashlights. They are a little harder to assemble vs the S2+ though due to the LED shelf, but it seems the shelf is better at heat dissipation. The E2L is also a little shorter than the S2+ and has a stainless steel bezel like the Convoy S3.
While ordering some parts last night from mountain electronics I noticed many things out of stock.
Probably the China situation is taking a toll on the supply chain.
A few drivers and mcpcb I wanted were not available.
Of particular notice was the supply of S2+ hosts that are cheaper than from the Convoy Store for some colors
The clear,sand,red and green hosts were sold out and the blue was down to a few left.
The purple,cyan and orange have not been available from MTN.
The reflector varies by color.
I have a s2+ Host that I’ll love to become a triple
I’ve also got a s2+ in the post soon to arrive sst40 at 5000k
I’d like to make a triple but I’m just shooting ideas atm
I kind of love convoys
I’ve also the 18350 tube
What’s the time difference on a sst40 between a 18650 and a 18350
I have the tube but not the 18350 batteries.I've only been using Samsung 30Q 18650 that are still on sale until Feb 27th.
The SST40 with Convoy 5A driver and Samsung 30Q gets hot and steps down in a few minutes.
For a triple build in an S2+ host I think the copper pill made by forum member Hoop is a must have compared to a spacer in a pill.
I've used the Dr Jones 17mm FET driver with button not spring and a MTN 17DD FET driver with beryllium copper spring bypassed.
The spot on the Dr Jones H17F driver for a spring is small so I opted for the brass button instead of a Qlite spring.
Tail cap springs should also be bypassed beryllium copper for low resistance..
The triple Samsung 5000k 90+Cri is a nice choice for LED but that's a more personal preference.
After assembling the parts in the host and feeling proud of my work I fully pressed the tail switch and to my unhappy surprize the light failed to turn on.After a few more clicks full and half still the light failed to go on. At this point I disassembled the light and carefully reassembled again>still not working.Once more I took it apart and put it back together with the same non functioning result. Now I sat in the chair collecting my thoughts of why Murphy's Law happened. After about 10 minutes of thought and frustration I took on of my other successfully built red S2+ out of the drawer and removed the tail cap.I put the red tail cap on the blue body and gave the switch a full press.The light came on and switch modes with half presses as it should.Hallelujah! Now I took the blue tail cap that didn't work on the blue body and put it on the red body....it worked. I took both tail caps apart and switch the switches from the blue to red and red to blue and now both lights work perfectly
Nah. G3s are flip-chips, no bond wires up-top, so they’re easy to dedome without killing the wires, but you have to watch out you don’t peel off the phosphor layer.
They’ve also got hideous angular tint-shift and will look like crap behind reflectors and even some TIRs.
Probably the retaining ring just needed some tightening to ensure good electrical contact
How much do the E2Ls go for? Whole or as a host?
I know S2+es used to be cheap as dirt, 8bux for a whole one at times (1B tint, though :confounded: ).
Plus, the different colors, shorty tubes, etc., make S2+es hella easy to customise.
The E2L’s hosts are more expensive, 18 or so. I think they lego with the convoy threads, so an 18350 would be nice, they come with a shelf and a nice SS bezel,so no need for additional pills and whatsoever, which make them shorter and very light.
You should message them to ask for one, they often close it on AE.
Thanks Lightbringer, I realized that after I researched the LED some more. Any idea on why the LED stopped working then?