Send it back, plain and simple, and get them to send you a new one. I can't believe how painful your posts make the FENIX sound.

It's one of the simplest pieces of tech equipment I have. I dump in NiMh batts, bring a spare set if I'm out for 2+ hours, and I'm good to go. Fabulous lighting all the way.

Get a new one, and try out your various batteries. ALL of my batts work, from the 1800mA thru the 2400mA, and the runtime does seem to correlated extremely well with the extra mAs on the higher capacity batts. I'll bet the customer service will be pretty good at Fenix as well, from what I've seen from other posts.