TheVirusSonetimes it just took a day or so for the capacitor (or whatever it is) in the tailcap to recharge. Just leave a full batterie in the flashlight for a while and try again.
TheVirusThat`s really bad......I would like to help you but I live in Germany:-(
Please try to contact Massdrop, I think they will help you!
Best regards!
TheVirusLumintop won't work with flat top batteries, unsure if you used these or not. As several have mentioned, the Eneloop Pro are an excellent choice. They are now marketed as Panasonic, however same as the previous branded Sanyo but with increased stats.