Fenix TK12

I have a Fenix TK12 that was always kept as a spare or backup flashlight. Very limited use. I went to use it and got no light from it. I checked the user manual and changed the batteries to fresh ones and it still wouldn't light. Then I checked to see the contact points and cleaned them with an alcohol swab even though they all seem clean and clear.

The bulb is in a sealed head so there's nothing I can do. I definitely don't want the hassle of sending it back to a dealer.

Is there anything else someone can think of that I've missed?

Which TK12 do you have, the original one from 2009/2010?
It could be a problem with the tailcap: make sure the retainer ring inside is tightened. If it still doesn't work, remove the tailcap and make a contact between the negative end of the battery and the threads: if it lights up, then the problem is in the tailcap. If you look around there's a sticky with all the basic troubleshooting options.

I have three "old" TK12 XP-G R5 and they have always been working flawlessly.

And here is the thread I was talking about - http://www.candlepowerforums.com/vb/showthread.php?338889-BASIC-FLASHLIGHT-TROUBLESHOOTING-GUIDE/

Thanks for all your help. I read through everything and tried what I could to no avail. Looks like this flashlight mysteriously died in its sleep.