My chrome v2.0 replacement unit arrived in my mailbox today. 
And... (wait for it...) It's a dud. Defective power switch.
When I drop a high-drain 18650 into the tube---positive end first, of course---and start to thread the bottom cap, as soon as the spring touches the base of the battery, the LED display lights up three times, letting me know that the unit "sees" the power source. Once the cap is threaded and snug, however, the 5-click power button turn-on sequence does nothing. Zero. Nada. 
I have two 1.5t Vtubes, so I know how to turn on one of these Young-June devices. And it ain't rocket science---I tried everything---soft clicks, hard clicks, fast clicks, slow clicks, 6 clicks, 27 clicks. I tried it with the bottom cap both threaded and not threaded (just touching the base, so that LED display does its three-flash confirmation). Useless. The unit does not turn on. Dead as a doornail. Batteries are fully charged and work perfectly in my other Vtubes. 
Is something different about the v2.0 start-up sequence? Am I missing something? Do I have to dance a jig while I'm pressing the power button? No instructions were included in the package, and I assumed that none were needed. Just to be thorough, I tried everything I could think of---more clicks, holding down both the "+" and "-" buttons, etc. 
Unless my brain has checked out into La-La-Land in some way I'm too crazed to realize, this isn't "user error." Just my bad luck to have been the one guy to get a bum unit. Like winning the lottery in reverse. LOL.