Yup, definitely a short. Are you using protected batteries?
Check if the LED wires are touching the reflector. Hopefully there is some sort of insulation there.
Yes exactly. If the battery wrapper is damaged, the battery could short against the barrel.
Do you have another battery to test with? First check that the reflector where it seats around the LED and make sure it's not shorting across the LED's wires.
-Garry
The label says protected, but it is an UltraFire…so with a grain of salt I take it. Honestly, I’d be surprised if it was protected as I bought the light, charger and battery for about $15 delivered.
In thinking about it…the reflector could indeed be shorting out the LED. When I received the light, there were a lot of threads showing between the reflector/LED/drop-in(?) and the pill(?)…think I am saying that correctly….so I hand-tightened them together. Perhaps I tightened it too hard?
I did hear a grinding sound when I screwed the head/lens(?) back down on top of that, which made me wince…but the light seemingly functioned properly, so I thought all was ok. Later, I did try to loosen the reflector from the pill…but couldn’t with just hand pressure.
I hope I didn’t ruin it!
and I did order some additional XTAR 2600 protected batteries, and XTAR2 II charger…and I must confess…some other nicely discounted lights. Egads…my wife is gonna kill me! I’ll have to engage in UPS sentry duty…
Reply #11 refers.
It appears to be another case of shorting.
Have I ruined the light or battery if it shorted?
I have shorted 2 of my lights that way, one 501B and a 502B
I opened the reflector and was able to unscrew it from the pill. The holes in the side of the emitter mount are not lined up well with the holes below them. As a result, the two wires are pinched in between and I am wondering if that has cut through the wire casing, hence the short. Could this be the cause? Has anyone seen this before? Other than that, I can’t see what might be causing the short. Really iritating. Wondering if I should just send the light back…
Could be. Is the insulation of the wires ok?
And was there a plastic disc on top of the LED for insulation? If not, there's your problem.
There was a plastic disc on top. The wires are such that I can’t tell if the insulation is cut or not. The disc that holds the emitter seems glued down to the metal below it, so I can’t move it to see. Since the metal and emitter disc holes are not lined up, the wires are immovable because they are pinched in between…make sense? Not sure if my terminology is correct yet…lol
And you can't just twist the LED star back so that the holes are aligned?
Can you perhaps post a picture?
I think the LED disc is bonded to the brass below. I have applied slight pressure, but I am afraid of twisting too hard. Hope it is easy to see in this pic.
It's likely glued down with thermal glue. You'd have to pry/chisel it up, check the wires, and re-glue it down.
What about probing around with a meter (on resistance mode) and check for 0.00 (a short) from that red lead at the emitter to the pill, to the black wire, etc. . .? Can you do this and report back?
-Garry
Ah ok, I was afraid that the star had lifted off the brass plate and the wires were pinched below it.
There is thermal adhesive below the star, that's why you can't twist it. Obviously it was manufatured that way. Dou you have a multimeter? You could check if there is an electric connection between the positive wire and the brass part.
Edit: Great minds think alike 
Thinking alike I see :)
-Garry
I have a cheapo multimeter from wallyworld that I can use. Resistance is measured in ohms…correct? Which setting on the mm do I put it on? It what order should I touch the leads to? Does that battery have to be in to test it? Thanks.
I set the mm to X1K. Touched the Pos. lead to Pos. wire, and Neg. lead to brass base, and the needle jumped to 20 ohms (guess I’m reading that right). Also not sure I have the meter zeroed properly…
Don't put the battery in the light. In fact, take the drop-in out and test it out of the body. Yes, ohms, x1k should be fine, but you might come down a setting lower. Order of the leads won't matter. You may get a reading across the LED (lead on each emitter wire) - that's ok. (Technically you should get a reading with leads placed one way and no reading with red & black leads swapped.) In order to take the reading across the LED out of the equation you'd have to unsolder one of the emitter wires. More interested in hearing what you read from positive (red) emitter lead to brass pill. Guess you should also place a meter lead on each input of driver (positive in center and ground ring on the outer edge).
-Garry
With meter setup as you described, you can take each meter lead and touch them together - you should read 0.00 (i.e. shorted). Sounds like you read 20,000 ohms (20 x 1k per the meter's setting). 20,000 ohms is not a short. You're looking for a very very low value.
-Garry